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The low-temperature crystal and mol­ecular structure analyses of two modifications of L-alanyl-L-tyrosyl-L-alanine with water, C15H21N3O5·2.63H2O [(I), at 9 K], and ethanol, C15H21N3O5·C2H5O [(II), at 20 K], solvent mol­ecules in the crystal lattice show that the overall conformations of both modifications of the title tripeptide are practically the same. Moreover, despite the presence of different solvent mol­ecules in the crystal lattice, the specific inter­molecular inter­actions characteristic for individual tripeptide mol­ecules of (I) and (II) are conserved. The crystal packing of the two modifications of Ala-Tyr-Ala differ from each other only in the solvent region. The tight arrangements of tripeptide mol­ecules seem to be responsible for similar displacement parameters for all non-H atoms, despite the different distances from the mol­ecular centre of mass. Comparison of the displacement parameters between the room- and low-temperature structures shows that an average Ueq value decrease of about 80% takes place at 9 K [for (I)] and 20 K [for (II)] with respect to room temperature.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270106018750/fa3016sup1.cif
Contains datablocks I, II, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270106018750/fa3016Isup2.hkl
Contains datablock I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270106018750/fa3016IIsup3.hkl
Contains datablock II

CCDC references: 618645; 618646

Comment top

In our ongoing comparative charge-density studies of oligopeptides, we became interested in the structures of tripeptides of the type L-Ala-Xxx-L-Ala, where Xxx is one of the 20 naturally encoded amino acids. First results have recently been obtained for Xxx = L-Ala (Rödel et al., 2006) and Xxx = Gly (Förster et al., 2005). In this paper, we describe the crystal and molecular structures of two modifications of L-alanyl-L-tyrosyl-L-alanine [L-Ala-L-Tyr-L-Ala, AYA; symbol according to the one-letter notation for amino acid sequences (IUPAC–IUB Commission on Biochemical Nomenclature, 1968)] with water, (I), and ethanol, (II), solvent molecules in the crystal structure. The different solvates were obtained using two crystallization routes for the title tripeptide (see Experimental).

The measurement temperature of 9 K [for (I)], realised by the recently installed He gas stream low-temperature set-up (Helijet) at beamline D3 of Hasylab (DESY, Hamburg, Germany), is infrequently observed in the literature. It prompted us to compare the equivalent isotropic displacement parameters of non-H atoms for the title tripeptide molecule at room temperature and at low temperature. Moreover, special attention has been focused on the molecular conformations of L-Ala-L-Tyr-L-Ala in comparison with the crystal structures of the analogous tripeptides previously reported (Förster et al., 2005; Padiyar & Seshadri, 1996; Fawcett et al., 1975). We are also interested in the crystal packing arrangements which are influenced by the presence of different solvent molecules in the crystal lattice.

The molecular structures, with the atom-numbering schemes, of both modifications of Ala-Tyr-Ala, (I) and (II), are shown in Figs. 1 and 2. The asymmetric unit of (I) consists of one tripeptide molecule and an average 2.6 water molecules (1 + 1 + 0.6), while for (II), the solvent consists of one ethanol molecule. In both cases, the Ala-Tyr-Ala molecules exist as zwitterions. Selected bond lengths and angles are given in Tables 1 and 3. The bond distances observed for both modifications are in good agreement and need no detailed disccussion. Table 5 presents the torsion angles, which characterize the backbone conformation of the tripeptide molecules. Among these, the C4—N3—C5—C6 and C4—N3—C5—C8 angles differ by slightly more than 15°, whereas the rest agree to within 10°. Hence, the molecular conformations are basically alike for both modifications. This means that the presence of different solvent molecules does not significantly disturb the overall conformation of the L-Ala-L-Tyr-L-Ala tripeptide.

Considering all published crystal structures of the type Ala-Xxx-Ala (where Xxx is one of the 20 naturally encoded amino acids), our special interest is focused on the conformation of the main peptide chain. It was found that the principal difference, in the conformation of two independent molecules of trialanine, is seen at the carboxyl terminal groups. Such a deformation is attributed to the requirements of hydrogen bonds and is reflected in the two values of the ψ3 angle (symbols in agreement with IUPAC–IUB Commission on Biochemical Nomenclature, 1970). The substantial variations (about 90° and more) between two forms of L-alanylglycyl-L-alanine, namely the hydrate and the solvent-free form, are visible for the ψ1 and ϕ3 torsion angles. Taking into consideration all the above-mentioned tripeptide structures, it seems that the essential conformational differences are noticeable for the Npep—Cα bonds, described by the ϕ2 and ϕ3 torsion parameters (Table 5), while all remaining backbone torsion angles are conserved and differ at most by 30–35°.

Fig. 3 presents equivalent displacement parameters (Ueq values) of all non H-atoms plotted versus their distances (r) from the molecular centre of mass for both modifications of Ala-Tyr-Ala, for the data sets measured at room temperature (Chęcińska et al., 2006) and at temperatures of 9 K [(I)] and 20 K [(II)]. The diagram reveals the influence of temperature on the refined model. It is interesting to note that, at all temperatures, there is no significant tendency for the Ueq values to increase for the outer atoms [with the exception of two outliers, C8 and O3, of the room-temperature structure of (II)], as is frequently observed for room-temperature structures (Meserschmidt et al., 2003; Wagner et al., 2002). The reason is obviously the tight integration of all tripeptide molecular fragments in intermolecular hydrogen bonding, as will be discussed later. The average Ueq values calculated for all non H-atoms at room temperature are 0.044 (9) and 0.055 (20) Å2 for (I) and (II), respectively; the corresponding averages at 9 K and 20 K are 0.0086 (14) and 0.0098 (20) Å2 for (I) and (II), respectively. Thus, compared with room temperature, an average decrease in Ueq of 80% has taken place at the lower temperatures. Similar reductions of displacement parameters when going to ultra-low temperatures of 10–20 K have frequently been observed, for example in our studies on an ergoline derivative (~80%; Luger & Zobel, 1993) and for an 18-crown-6–KClO4 complex (85–90%; Luger et al., 1992).

It is worth mentioning the unusually high fraction of significant reflections with I > 2σ(I), which is between 98 and 99% for both data sets. This is of course the result of the very favourable experimental conditions, especially the low data-collection temperature, which favours an intensity increase of the high-order reflections.

The structures of oligopeptides offer the possibility of a wide variety of potential intermolecular interactions. Additionally, the number of hydrogen bonds increases due to the presence of the solvent molecules (water and ethanol) in the crystal lattice. To facilitate better understanding of the similarities and differences in the crystal packing of (I) and (II), we now describe the hydrogen-bonding networks, first separately for the tripeptide molecules and then together with solvent. The hydrogen-bonding geometries are presented in Tables 2 and 4, for (I) and (II), respectively. Examining the specific intermolecular interactions characteristic for individual tripeptide molecules of (I) and (II) indicates that they are very similar in both cases. Ala-Tyr-Ala possesses six potential hydrogen-bonding donors (–NH or –OH) and five O atoms (–OH, CO or –COO), which are acceptors. As a result, the crystal structures of (I) and (II) contain three Namm—H···O intermolecular hydrogen bonds. Based on geometric criteria, the N1—H11C···O2iv hydrogen bond (see Table 4 for symmetry code) seems to be the strongest, with a donor···acceptor distance of 2.748 (1) Å for structure (II). The remaining Namm—H···O interactions are characterized by somewhat longer N···O distances, which are in the range 2.786 (1)–2.873 (1) Å. The amide N—H bonds form the next set of interactions, which are typical for tripeptide molecules. Their geometries are roughly comparable for the water and ethanol modifications. In conclusion, it is worth mentioning that, considering only interactions between the tripeptide molecules, the hydrogen-bonded motifs are the same in both structures. The hydroxyl group (O5—H15) of the tyrosine fragment acts as a hydrogen-bond donor to O atoms of the solvent molecule, water and ethanol in (I) and (II), respectively. These O—H···O hydrogen bonds appear to be the strongest of all non-covalent interactions in the present structures.

In the crystal structure of Ala-Tyr-Ala, (I), there are two fully occupied water molecules. Each of them is involved in two interactions as a donor; atom O7 is an acceptor twice, whereas atom O6 is an acceptor only once. The third water molecule, which appears approximately twice every three unit cells, participates in only one (O8—H81···O7) hydrogen bond. In contrast, the hydrogen-bonding network of (II), with ethanol as the solvent, is rather simple. Atom O6 of the ethanol molecule participates in the above-mentioned interaction with the tyrosine hydroxyl group (O5—H15···O6i), as well as in O6—H16···O3ii interactions. Figs. 4 and 5 present the crystal packing of the reported structures projected onto the ac plane.

In closing, it can be seen from the figures that the arrangements of the molecules of these two modifications of Ala-Tyr-Ala, (I) and (II), differ from each other only in the solvent region.

Experimental top

The title tripeptide L-alanyl-L-tyrosyl-L-alanine was obtained from Bachem (Germany). Crystallization from water by slow evaporation yielded crystals of modification (I). Crystals of modification (II) were prepared by diffusion of ethanol into an aqueous solution of the tripeptide at room temperature.

Refinement top

One water molecule appears to be partially occupied in the crystal structure of (I). A common occupancy factor for the O atom (O8) and the two H atoms (H81 and H82) was refined freely to 0.628 (4) without any restraints. Due to the absence of significant anomalous scattering effects, 4464 and 4366 Friedel pairs were merged for (I) and (II), respectively. The absolute configuration of the purchased material was known.

Computing details top

Data collection: MarCCD (Paulmann & Morgenroth, 2006) for (I); SMART (Bruker, 1997–2001) for (II). Cell refinement: XDS (Kabsch, 1993) for (I); SMART for (II). Data reduction: XDS for (I); SAINT (Bruker, 1997–2001) and SADABS (Bruker, 1997–2001) for (II). For both compounds, program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: PLATON.

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
[Figure 2] Fig. 2. The molecular structure of (II), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
[Figure 3] Fig. 3. Equivalent isotropic displacement parameters Ueq2) plotted versus the corresponding atomic distances r (Å) from the molecular centre of mass for the water and ethanol modifications of AYA at room temperature and at 9 K [(I)] and 20 K [(II)].
[Figure 4] Fig. 4. Part of the crystal structure of (I), showing the hydrogen-bonding network, projected on to the ac plane. N and O atoms are shaded. For clarity, H atoms bonded to C atoms have been omitted.
[Figure 5] Fig. 5. Part of the crystal structure of (II), showing the hydrogen-bonding network, projected on to the ac plane. and O atoms are shaded. For clarity, H atoms bonded to C atoms have been omitted.
(I) L-alanyl-L-tyrosyl-L-alanine 2.63-hydrate top
Crystal data top
C15H21N3O5·2.628H2OF(000) = 397
Mr = 370.69Dx = 1.301 Mg m3
Monoclinic, P21Synchrotron radiation, λ = 0.50 Å
Hall symbol: P 2ybCell parameters from 1613 reflections
a = 8.121 (3) Åθ = 1.9–19.4°
b = 9.299 (4) ŵ = 0.06 mm1
c = 12.532 (5) ÅT = 9 K
β = 91.21 (2)°Needle, colourless
V = 946.2 (7) Å30.54 × 0.25 × 0.13 mm
Z = 2
Data collection top
Huber
diffractometer with MarCCD detector
4945 reflections with I > 2σ(I)
Radiation source: synchrotronRint = 0.044
Graphite monochromatorθmax = 25.0°, θmin = 1.1°
ϕ scansh = 1313
9540 measured reflectionsk = 1515
5019 independent reflectionsl = 2121
Refinement top
Refinement on F2Secondary atom site location: structure-invariant direct methods
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.024All H-atom parameters refined
wR(F2) = 0.068 w = 1/[σ2(Fo2) + (0.0499P)2 + 0.0316P]
where P = (Fo2 + 2Fc2)/3
S = 1.11(Δ/σ)max = 0.001
5019 reflectionsΔρmax = 0.45 e Å3
344 parametersΔρmin = 0.24 e Å3
1 restraintAbsolute structure: rm
Primary atom site location: structure-invariant direct methods
Crystal data top
C15H21N3O5·2.628H2OV = 946.2 (7) Å3
Mr = 370.69Z = 2
Monoclinic, P21Synchrotron radiation, λ = 0.50 Å
a = 8.121 (3) ŵ = 0.06 mm1
b = 9.299 (4) ÅT = 9 K
c = 12.532 (5) Å0.54 × 0.25 × 0.13 mm
β = 91.21 (2)°
Data collection top
Huber
diffractometer with MarCCD detector
4945 reflections with I > 2σ(I)
9540 measured reflectionsRint = 0.044
5019 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0241 restraint
wR(F2) = 0.068All H-atom parameters refined
S = 1.11Δρmax = 0.45 e Å3
5019 reflectionsΔρmin = 0.24 e Å3
344 parametersAbsolute structure: rm
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/UeqOcc. (<1)
O10.06035 (7)0.37956 (6)0.47927 (4)0.00942 (8)
O20.00628 (7)0.73348 (6)0.76658 (4)0.00960 (8)
O30.17783 (6)0.59346 (6)1.02578 (4)0.00998 (8)
O40.02513 (6)0.70248 (5)1.11477 (4)0.00792 (8)
O50.61147 (6)1.02747 (6)0.68076 (4)0.01050 (8)
N10.04654 (7)0.52309 (6)0.29184 (4)0.00788 (8)
N20.04051 (7)0.58477 (6)0.57845 (4)0.00723 (8)
N30.03024 (7)0.52213 (6)0.85565 (4)0.00704 (8)
C10.02046 (7)0.59748 (7)0.38758 (4)0.00667 (9)
C20.03198 (7)0.51064 (7)0.48649 (4)0.00656 (9)
C30.08504 (7)0.51225 (6)0.67848 (4)0.00673 (9)
C40.01586 (7)0.60003 (7)0.77079 (4)0.00661 (9)
C50.10079 (7)0.58966 (7)0.94938 (4)0.00662 (8)
C60.03030 (7)0.63138 (7)1.03519 (4)0.00650 (8)
C70.20806 (8)0.60620 (8)0.37742 (5)0.01114 (10)
C80.23060 (8)0.49022 (8)0.99806 (5)0.01105 (10)
C200.27471 (8)0.48933 (7)0.69096 (5)0.00813 (9)
C210.37347 (8)0.62734 (7)0.69027 (5)0.00793 (9)
C220.40865 (8)0.70208 (8)0.78569 (5)0.00980 (10)
C230.49152 (8)0.83439 (8)0.78489 (5)0.01009 (10)
C240.53805 (8)0.89353 (7)0.68726 (5)0.00848 (9)
C250.50980 (8)0.81836 (7)0.59189 (5)0.00955 (10)
C260.42775 (8)0.68600 (7)0.59367 (5)0.00904 (9)
H10.0288 (19)0.688 (2)0.3896 (12)0.016 (3)*
H30.0330 (17)0.4168 (16)0.6823 (11)0.010 (3)*
H50.154 (2)0.674 (2)0.9252 (13)0.019 (4)*
H7A0.253 (2)0.510 (2)0.3775 (13)0.019 (3)*
H7B0.253 (2)0.657 (2)0.4393 (14)0.024 (4)*
H7C0.243 (2)0.650 (2)0.3091 (15)0.030 (5)*
H8A0.182 (2)0.402 (2)1.0187 (14)0.020 (4)*
H8B0.280 (2)0.533 (2)1.0564 (15)0.025 (4)*
H8C0.318 (2)0.473 (2)0.9479 (15)0.028 (4)*
H11C0.012 (2)0.434 (2)0.2821 (14)0.022 (4)*
H11B0.155 (2)0.519 (2)0.2969 (13)0.020 (4)*
H11A0.018 (2)0.579 (2)0.2303 (13)0.020 (4)*
H120.0172 (18)0.6775 (19)0.5781 (12)0.014 (3)*
H130.020 (2)0.434 (2)0.8576 (13)0.021 (4)*
H150.585 (2)1.082 (2)0.7330 (15)0.028 (4)*
H20A0.300 (2)0.436 (2)0.7588 (14)0.021 (4)*
H20B0.309 (2)0.425 (2)0.6326 (14)0.024 (4)*
H220.3720 (18)0.6618 (18)0.8511 (12)0.014 (3)*
H230.510 (2)0.887 (2)0.8474 (14)0.021 (4)*
H250.5437 (19)0.866 (2)0.5280 (12)0.019 (4)*
H260.399 (2)0.6352 (19)0.5279 (13)0.017 (3)*
O60.32383 (6)0.34130 (6)0.94027 (4)0.01026 (8)
H610.289 (2)0.420 (2)0.9633 (14)0.024 (4)*
H620.232 (3)0.295 (2)0.9209 (16)0.032 (5)*
O70.58445 (7)0.20851 (6)0.84060 (4)0.01131 (8)
H710.658 (2)0.179 (2)0.8852 (15)0.026 (4)*
H720.513 (3)0.249 (3)0.8723 (18)0.041 (6)*
O80.71471 (12)0.37599 (12)0.66470 (8)0.0159 (3)0.628 (4)
H810.679 (4)0.337 (4)0.716 (3)0.030 (7)*0.628 (4)
H820.673 (4)0.451 (5)0.652 (3)0.039 (9)*0.628 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0156 (2)0.00504 (17)0.00765 (17)0.00096 (15)0.00012 (14)0.00056 (14)
O20.0152 (2)0.00476 (17)0.00892 (18)0.00081 (15)0.00213 (14)0.00034 (14)
O30.00860 (17)0.0104 (2)0.01095 (18)0.00120 (15)0.00054 (14)0.00251 (16)
O40.01135 (18)0.00675 (18)0.00570 (15)0.00097 (14)0.00109 (13)0.00129 (13)
O50.01189 (18)0.00853 (19)0.01113 (18)0.00185 (15)0.00158 (14)0.00272 (15)
N10.01100 (19)0.00686 (19)0.00582 (17)0.00108 (16)0.00128 (14)0.00030 (15)
N20.01216 (19)0.00519 (18)0.00434 (17)0.00038 (15)0.00034 (14)0.00018 (14)
N30.01139 (19)0.00499 (18)0.00483 (17)0.00035 (15)0.00218 (14)0.00042 (14)
C10.0095 (2)0.0054 (2)0.00518 (18)0.00096 (17)0.00055 (15)0.00041 (16)
C20.00901 (19)0.0056 (2)0.00509 (19)0.00003 (16)0.00080 (14)0.00009 (15)
C30.0102 (2)0.0053 (2)0.00473 (18)0.00031 (17)0.00125 (15)0.00009 (15)
C40.0089 (2)0.0060 (2)0.00497 (18)0.00029 (16)0.00099 (15)0.00022 (16)
C50.00850 (19)0.0060 (2)0.00544 (18)0.00008 (16)0.00123 (15)0.00094 (16)
C60.00891 (19)0.0050 (2)0.00558 (19)0.00016 (16)0.00097 (15)0.00015 (15)
C70.0090 (2)0.0132 (3)0.0112 (2)0.00165 (19)0.00012 (17)0.0002 (2)
C80.0125 (2)0.0101 (2)0.0108 (2)0.00381 (19)0.00457 (18)0.00275 (19)
C200.0101 (2)0.0070 (2)0.0073 (2)0.00115 (17)0.00113 (16)0.00039 (17)
C210.0091 (2)0.0081 (2)0.00659 (19)0.00007 (17)0.00115 (15)0.00030 (17)
C220.0121 (2)0.0107 (2)0.0066 (2)0.00095 (19)0.00069 (16)0.00052 (18)
C230.0119 (2)0.0109 (2)0.0074 (2)0.0010 (2)0.00045 (17)0.00190 (18)
C240.0087 (2)0.0083 (2)0.0084 (2)0.00040 (17)0.00082 (16)0.00146 (17)
C250.0124 (2)0.0090 (2)0.0073 (2)0.00179 (18)0.00233 (16)0.00122 (17)
C260.0119 (2)0.0086 (2)0.0068 (2)0.00115 (18)0.00178 (16)0.00114 (17)
O60.01022 (18)0.00865 (19)0.01197 (19)0.00046 (15)0.00143 (14)0.00076 (15)
O70.01121 (18)0.0126 (2)0.01007 (17)0.00237 (16)0.00020 (14)0.00210 (16)
O80.0152 (4)0.0180 (5)0.0147 (4)0.0025 (3)0.0030 (3)0.0013 (3)
Geometric parameters (Å, º) top
O1—C21.2442 (9)C7—H7A0.961 (19)
O2—C41.2444 (9)C7—H7B0.983 (18)
O3—C61.2568 (9)C7—H7C0.985 (19)
O4—C61.2859 (8)C8—H8A0.946 (18)
O5—C241.3840 (10)C8—H8B0.930 (19)
O5—H150.859 (19)C8—H8C0.950 (19)
N1—C11.4971 (9)C20—C211.5135 (10)
N1—H11C0.89 (2)C20—H20A1.003 (18)
N1—H11B0.883 (17)C20—H20B0.986 (19)
N1—H11A0.954 (17)C21—C261.4071 (10)
N2—C21.3434 (9)C21—C221.4073 (10)
N2—C31.4622 (9)C22—C231.4025 (11)
N2—H120.883 (17)C22—H220.955 (16)
N3—C41.3463 (9)C23—C241.4006 (10)
N3—C51.4598 (9)C23—H230.933 (18)
N3—H130.82 (2)C24—C251.3993 (10)
C1—C71.5283 (11)C25—C261.4000 (11)
C1—C21.5322 (9)C25—H250.962 (16)
C1—H10.934 (18)C26—H260.974 (17)
C3—C41.5322 (9)O6—H610.838 (19)
C3—C201.5595 (11)O6—H620.89 (2)
C3—H30.984 (15)O7—H710.855 (19)
C5—C81.5381 (10)O7—H720.80 (2)
C5—C61.5466 (10)O8—H810.80 (4)
C5—H50.943 (18)O8—H820.79 (4)
C24—O5—H15112.1 (14)C1—C7—H7A109.0 (10)
C1—N1—H11C115.2 (11)C1—C7—H7B110.0 (10)
C1—N1—H11B110.1 (11)H7A—C7—H7B107.5 (15)
H11C—N1—H11B106.1 (17)C1—C7—H7C111.3 (11)
C1—N1—H11A108.1 (11)H7A—C7—H7C106.5 (16)
H11C—N1—H11A109.4 (15)H7B—C7—H7C112.4 (16)
H11B—N1—H11A107.7 (15)C5—C8—H8A110.4 (11)
C2—N2—C3120.41 (6)C5—C8—H8B111.2 (12)
C2—N2—H12119.3 (10)H8A—C8—H8B109.9 (16)
C3—N2—H12120.3 (10)C5—C8—H8C110.2 (12)
C4—N3—C5121.63 (6)H8A—C8—H8C109.6 (17)
C4—N3—H13121.9 (12)H8B—C8—H8C105.4 (16)
C5—N3—H13116.5 (12)C21—C20—C3113.95 (5)
N1—C1—C7109.65 (5)C21—C20—H20A109.2 (10)
N1—C1—C2107.77 (5)C3—C20—H20A109.5 (10)
C7—C1—C2110.79 (5)C21—C20—H20B110.4 (11)
N1—C1—H1106.0 (10)C3—C20—H20B107.5 (11)
C7—C1—H1112.3 (10)H20A—C20—H20B105.9 (15)
C2—C1—H1110.0 (10)C26—C21—C22118.55 (6)
O1—C2—N2123.97 (6)C26—C21—C20120.62 (6)
O1—C2—C1120.42 (5)C22—C21—C20120.80 (6)
N2—C2—C1115.60 (6)C23—C22—C21121.07 (6)
N2—C3—C4108.28 (5)C23—C22—H22120.6 (10)
N2—C3—C20112.02 (5)C21—C22—H22118.3 (10)
C4—C3—C20111.98 (5)C24—C23—C22119.28 (6)
N2—C3—H3111.0 (8)C24—C23—H23119.0 (11)
C4—C3—H3106.2 (9)C22—C23—H23121.6 (11)
C20—C3—H3107.2 (8)O5—C24—C25117.54 (6)
O2—C4—N3123.50 (6)O5—C24—C23121.96 (6)
O2—C4—C3121.52 (5)C25—C24—C23120.50 (7)
N3—C4—C3114.97 (6)C24—C25—C26119.68 (6)
N3—C5—C8110.15 (5)C24—C25—H25115.8 (11)
N3—C5—C6113.04 (6)C26—C25—H25124.4 (11)
C8—C5—C6110.03 (5)C25—C26—C21120.82 (6)
N3—C5—H5106.5 (10)C25—C26—H26121.2 (10)
C8—C5—H5108.4 (10)C21—C26—H26117.8 (10)
C6—C5—H5108.6 (11)H61—O6—H62103.3 (18)
O3—C6—O4124.54 (6)H71—O7—H72109 (2)
O3—C6—C5120.53 (6)H81—O8—H82114 (3)
O4—C6—C5114.91 (6)
C3—N2—C2—O10.09 (9)C8—C5—C6—O3116.19 (7)
C3—N2—C2—C1178.39 (5)N3—C5—C6—O4174.16 (5)
N1—C1—C2—O126.26 (8)C8—C5—C6—O462.25 (7)
C7—C1—C2—O193.70 (7)N2—C3—C20—C2159.76 (7)
N1—C1—C2—N2155.20 (5)C4—C3—C20—C2162.11 (7)
C7—C1—C2—N284.84 (7)C3—C20—C21—C2688.59 (7)
C2—N2—C3—C4156.19 (5)C3—C20—C21—C2289.44 (7)
C2—N2—C3—C2079.85 (7)C26—C21—C22—C231.94 (10)
C5—N3—C4—O21.91 (10)C20—C21—C22—C23176.13 (6)
C5—N3—C4—C3179.08 (5)C21—C22—C23—C240.77 (10)
N2—C3—C4—O233.58 (8)C22—C23—C24—O5176.18 (6)
C20—C3—C4—O290.41 (7)C22—C23—C24—C253.21 (10)
N2—C3—C4—N3147.39 (5)O5—C24—C25—C26176.52 (6)
C20—C3—C4—N388.62 (6)C23—C24—C25—C262.89 (10)
C4—N3—C5—C8145.72 (6)C24—C25—C26—C210.11 (10)
C4—N3—C5—C690.75 (7)C22—C21—C26—C252.27 (9)
N3—C5—C6—O37.41 (8)C20—C21—C26—C25175.81 (6)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O5—H15···O7i0.86 (2)1.79 (2)2.629 (1)165 (2)
O6—H61···O30.84 (2)2.02 (2)2.847 (1)172 (2)
O6—H62···O4ii0.89 (2)1.93 (3)2.821 (1)176 (2)
O7—H71···O3iii0.86 (2)1.90 (2)2.746 (1)173 (2)
O7—H72···O60.80 (2)1.97 (2)2.771 (1)175 (3)
O8—H81···O70.80 (4)2.12 (4)2.916 (1)173 (4)
N1—H11A···O4iv0.96 (2)1.88 (2)2.827 (1)175 (2)
N1—H11B···O5v0.88 (2)1.91 (2)2.792 (1)174 (2)
N1—H11C···O2vi0.88 (2)1.97 (2)2.821 (1)163 (2)
N2—H12···O1vii0.88 (2)2.10 (2)2.947 (2)160 (2)
N3—H13···O4ii0.82 (2)2.21 (2)3.028 (2)172 (2)
Symmetry codes: (i) x, y+1, z; (ii) x, y1/2, z+2; (iii) x+1, y1/2, z+2; (iv) x, y, z1; (v) x+1, y1/2, z+1; (vi) x, y1/2, z+1; (vii) x, y+1/2, z+1.
(II) L-alanyl-L-tyrosyl-L-alanine ethanol solvate top
Crystal data top
C15H21N3O5·C2H6OF(000) = 396
Mr = 369.42Dx = 1.243 Mg m3
Monoclinic, P21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ybCell parameters from 1447 reflections
a = 8.845 (2) Åθ = 1.2–15.8°
b = 9.057 (2) ŵ = 0.09 mm1
c = 12.364 (3) ÅT = 20 K
β = 94.56 (3)°Prism, colourless
V = 987.3 (4) Å30.4 × 0.25 × 0.2 mm
Z = 2
Data collection top
Huber four-circle
diffractometer with Bruker SMART Apex CCD area-detector
5178 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.035
Graphite monochromatorθmax = 37.0°, θmin = 1.7°
ϕ scansh = 1414
9710 measured reflectionsk = 1514
5258 independent reflectionsl = 2020
Refinement top
Refinement on F2Secondary atom site location: structure-invariant direct methods
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.029All H-atom parameters refined
wR(F2) = 0.077 w = 1/[σ2(Fo2) + (0.0564P)2 + 0.0452P]
where P = (Fo2 + 2Fc2)/3
S = 1.10(Δ/σ)max = 0.001
5258 reflectionsΔρmax = 0.50 e Å3
343 parametersΔρmin = 0.19 e Å3
2 restraintsAbsolute structure: rm
Primary atom site location: structure-invariant direct methods
Crystal data top
C15H21N3O5·C2H6OV = 987.3 (4) Å3
Mr = 369.42Z = 2
Monoclinic, P21Mo Kα radiation
a = 8.845 (2) ŵ = 0.09 mm1
b = 9.057 (2) ÅT = 20 K
c = 12.364 (3) Å0.4 × 0.25 × 0.2 mm
β = 94.56 (3)°
Data collection top
Huber four-circle
diffractometer with Bruker SMART Apex CCD area-detector
5178 reflections with I > 2σ(I)
9710 measured reflectionsRint = 0.035
5258 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0292 restraints
wR(F2) = 0.077All H-atom parameters refined
S = 1.10Δρmax = 0.50 e Å3
5258 reflectionsΔρmin = 0.19 e Å3
343 parametersAbsolute structure: rm
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.42025 (7)0.41657 (6)0.48566 (4)0.01016 (9)
O20.50363 (7)0.03376 (6)0.76064 (4)0.01123 (9)
O30.32839 (7)0.22453 (7)1.03294 (5)0.01133 (9)
O40.46140 (7)0.05567 (7)1.13499 (4)0.00951 (9)
O50.08155 (7)0.22438 (7)0.67985 (5)0.01151 (9)
O60.08376 (7)0.13907 (7)0.13284 (5)0.01257 (10)
N10.40141 (7)0.25752 (7)0.29610 (5)0.00849 (9)
N20.46622 (7)0.20696 (7)0.58601 (4)0.00793 (9)
N30.52908 (7)0.22916 (7)0.87748 (5)0.00809 (9)
C10.49715 (8)0.19911 (8)0.39217 (5)0.00795 (10)
C20.45654 (8)0.28409 (8)0.49275 (5)0.00735 (9)
C30.43687 (8)0.27494 (8)0.68946 (5)0.00729 (9)
C40.49528 (7)0.16845 (7)0.77971 (5)0.00710 (9)
C50.56879 (8)0.14001 (8)0.97423 (5)0.00817 (10)
C60.44057 (7)0.14022 (8)1.05208 (5)0.00762 (9)
C70.66571 (8)0.21795 (10)0.37416 (6)0.01203 (11)
C80.71655 (9)0.19542 (11)1.03487 (6)0.01431 (13)
C200.26481 (8)0.30847 (8)0.69791 (5)0.00853 (10)
C210.16606 (8)0.17168 (8)0.69369 (5)0.00829 (10)
C220.13990 (8)0.09578 (8)0.78985 (5)0.00943 (10)
C230.05527 (8)0.03487 (8)0.78698 (5)0.01021 (11)
C240.00400 (8)0.09195 (8)0.68672 (5)0.00924 (10)
C250.01633 (8)0.01536 (9)0.59034 (5)0.01064 (11)
C260.10136 (8)0.11531 (8)0.59433 (5)0.00974 (10)
C310.08069 (10)0.01990 (10)0.13299 (7)0.01596 (13)
C320.13330 (10)0.08282 (11)0.24398 (8)0.01866 (14)
H10.4740 (18)0.102 (2)0.4028 (14)0.013 (3)*
H30.4955 (17)0.3668 (19)0.6988 (12)0.010 (3)*
H50.579 (2)0.042 (2)0.9507 (14)0.017 (4)*
H7A0.726 (2)0.182 (2)0.4322 (15)0.022 (4)*
H7B0.688 (2)0.315 (3)0.3675 (16)0.028 (5)*
H7C0.692 (2)0.162 (2)0.3095 (14)0.018 (4)*
H8A0.707 (2)0.292 (2)1.0593 (15)0.025 (4)*
H8B0.742 (2)0.141 (3)1.1018 (18)0.034 (5)*
H8C0.7979 (19)0.191 (2)0.9897 (14)0.017 (4)*
H11A0.409 (2)0.189 (3)0.2391 (16)0.029 (5)*
H11B0.3103 (18)0.264 (2)0.3084 (13)0.013 (3)*
H11C0.428 (2)0.338 (2)0.2779 (14)0.019 (4)*
H120.490 (2)0.117 (2)0.5838 (15)0.019 (4)*
H130.5212 (18)0.3221 (10)0.8816 (12)0.011 (3)*
H150.070 (2)0.263 (3)0.7389 (17)0.029 (5)*
H160.160 (3)0.167 (3)0.098 (2)0.041 (6)*
H230.039 (2)0.088 (2)0.8538 (14)0.019 (4)*
H220.183 (2)0.137 (2)0.8566 (15)0.025 (4)*
H260.118 (2)0.172 (2)0.5247 (14)0.018 (4)*
H250.0235 (19)0.054 (2)0.5227 (13)0.015 (4)*
H20A0.261 (2)0.363 (2)0.7651 (14)0.019 (4)*
H20B0.2321 (19)0.373 (2)0.6419 (13)0.013 (3)*
H31A0.028 (2)0.046 (3)0.1128 (17)0.032 (5)*
H31B0.147 (2)0.055 (3)0.0776 (16)0.026 (5)*
H32A0.065 (2)0.042 (2)0.3013 (15)0.023 (4)*
H32B0.235 (2)0.057 (3)0.2663 (18)0.033 (5)*
H32C0.130 (2)0.193 (3)0.2403 (16)0.029 (5)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0158 (2)0.00629 (19)0.00853 (18)0.00100 (16)0.00179 (15)0.00002 (15)
O20.0181 (2)0.0060 (2)0.00944 (18)0.00156 (17)0.00032 (16)0.00076 (16)
O30.0115 (2)0.0121 (2)0.01054 (19)0.00330 (17)0.00190 (15)0.00217 (17)
O40.0142 (2)0.0081 (2)0.00635 (17)0.00010 (17)0.00166 (14)0.00161 (15)
O50.0132 (2)0.0096 (2)0.0116 (2)0.00326 (17)0.00072 (16)0.00106 (17)
O60.0124 (2)0.0111 (2)0.0146 (2)0.00058 (18)0.00362 (17)0.00234 (18)
N10.0112 (2)0.0079 (2)0.00635 (18)0.00008 (17)0.00031 (15)0.00020 (16)
N20.0126 (2)0.0064 (2)0.00491 (18)0.00045 (17)0.00144 (15)0.00025 (16)
N30.0124 (2)0.0067 (2)0.00515 (18)0.00008 (17)0.00054 (15)0.00015 (16)
C10.0107 (2)0.0074 (2)0.0057 (2)0.00046 (19)0.00069 (17)0.00003 (18)
C20.0093 (2)0.0071 (2)0.0057 (2)0.00064 (18)0.00112 (16)0.00003 (17)
C30.0103 (2)0.0061 (2)0.0056 (2)0.00023 (18)0.00111 (16)0.00010 (17)
C40.0090 (2)0.0065 (2)0.0059 (2)0.00006 (18)0.00113 (16)0.00012 (17)
C50.0105 (2)0.0084 (2)0.00565 (19)0.00068 (19)0.00108 (17)0.00104 (18)
C60.0099 (2)0.0069 (2)0.00608 (19)0.00043 (19)0.00106 (16)0.00002 (18)
C70.0102 (2)0.0150 (3)0.0111 (2)0.0010 (2)0.00210 (19)0.0001 (2)
C80.0113 (3)0.0204 (3)0.0109 (2)0.0030 (2)0.0012 (2)0.0044 (2)
C200.0095 (2)0.0071 (2)0.0090 (2)0.00014 (18)0.00099 (17)0.00002 (18)
C210.0093 (2)0.0077 (2)0.0078 (2)0.00023 (18)0.00078 (17)0.00047 (18)
C220.0111 (2)0.0096 (2)0.0075 (2)0.0017 (2)0.00075 (18)0.00049 (19)
C230.0119 (3)0.0105 (3)0.0081 (2)0.0017 (2)0.00065 (18)0.0009 (2)
C240.0097 (2)0.0086 (3)0.0094 (2)0.00161 (19)0.00074 (18)0.0006 (2)
C250.0124 (3)0.0111 (3)0.0083 (2)0.0022 (2)0.00029 (19)0.0005 (2)
C260.0120 (2)0.0095 (3)0.0077 (2)0.0017 (2)0.00027 (18)0.00099 (19)
C310.0160 (3)0.0116 (3)0.0207 (3)0.0014 (2)0.0041 (2)0.0049 (3)
C320.0156 (3)0.0130 (3)0.0277 (4)0.0009 (3)0.0037 (3)0.0034 (3)
Geometric parameters (Å, º) top
O1—C21.2434 (9)C5—H50.94 (2)
O2—C41.2457 (9)C7—H7A0.921 (19)
O3—C61.2594 (9)C7—H7B0.91 (2)
O4—C61.2811 (9)C7—H7C0.989 (18)
O5—C241.3809 (10)C8—H8A0.93 (2)
O5—H150.81 (2)C8—H8B0.98 (2)
O6—C311.4400 (11)C8—H8C0.947 (16)
O6—H160.87 (2)C20—C211.5142 (10)
N1—C11.4993 (10)C20—H20A0.970 (18)
N1—H11A0.94 (2)C20—H20B0.935 (17)
N1—H11B0.834 (16)C21—C221.4083 (10)
N1—H11C0.80 (2)C21—C261.4091 (10)
N2—C21.3451 (9)C22—C231.3991 (11)
N2—C31.4612 (9)C22—H220.954 (19)
N2—H120.85 (2)C23—C241.4056 (10)
N3—C41.3399 (9)C23—H230.978 (18)
N3—C51.4627 (9)C24—C251.4026 (10)
N3—H130.847 (9)C25—C261.4010 (11)
C1—C21.5293 (10)C25—H250.949 (17)
C1—C71.5344 (11)C26—H261.022 (18)
C1—H10.919 (19)C31—C321.5241 (14)
C3—C41.5331 (10)C31—H31A1.00 (2)
C3—C201.5635 (10)C31—H31B0.99 (2)
C3—H30.982 (17)C32—H32A1.031 (19)
C5—C81.5382 (11)C32—H32B0.95 (2)
C5—C61.5448 (10)C32—H32C1.00 (2)
C24—O5—H15107.2 (16)H7A—C7—H7C106.7 (16)
C31—O6—H16107.6 (18)H7B—C7—H7C110.7 (18)
C1—N1—H11A106.9 (13)C5—C8—H8A111.6 (12)
C1—N1—H11B112.0 (11)C5—C8—H8B112.1 (14)
H11A—N1—H11B108.0 (17)H8A—C8—H8B103.0 (18)
C1—N1—H11C112.3 (13)C5—C8—H8C110.8 (11)
H11A—N1—H11C110.3 (18)H8A—C8—H8C109.0 (17)
H11B—N1—H11C107.3 (18)H8B—C8—H8C110.1 (17)
C2—N2—C3121.87 (6)C21—C20—C3113.62 (6)
C2—N2—H12118.3 (12)C21—C20—H20A112.7 (12)
C3—N2—H12119.9 (12)C3—C20—H20A105.0 (11)
C4—N3—C5122.22 (6)C21—C20—H20B110.1 (10)
C4—N3—H13116.7 (10)C3—C20—H20B108.6 (10)
C5—N3—H13121.0 (10)H20A—C20—H20B106.5 (15)
N1—C1—C2108.19 (6)C22—C21—C26118.46 (6)
N1—C1—C7109.87 (6)C22—C21—C20120.22 (6)
C2—C1—C7110.84 (6)C26—C21—C20121.30 (6)
N1—C1—H1109.5 (10)C23—C22—C21120.99 (6)
C2—C1—H1107.4 (11)C23—C22—H22121.5 (13)
C7—C1—H1111.0 (10)C21—C22—H22117.5 (13)
O1—C2—N2124.06 (6)C22—C23—C24119.65 (6)
O1—C2—C1120.29 (6)C22—C23—H23120.7 (11)
N2—C2—C1115.64 (6)C24—C23—H23119.6 (11)
N2—C3—C4107.40 (6)O5—C24—C25118.29 (6)
N2—C3—C20112.46 (6)O5—C24—C23121.49 (6)
C4—C3—C20110.30 (6)C25—C24—C23120.22 (7)
N2—C3—H3109.3 (9)C26—C25—C24119.51 (6)
C4—C3—H3107.7 (9)C26—C25—H25120.3 (11)
C20—C3—H3109.6 (9)C24—C25—H25120.1 (11)
O2—C4—N3124.07 (6)C25—C26—C21121.09 (6)
O2—C4—C3119.99 (6)C25—C26—H26120.4 (11)
N3—C4—C3115.88 (6)C21—C26—H26118.5 (11)
N3—C5—C8110.98 (6)O6—C31—C32111.75 (7)
N3—C5—C6111.62 (6)O6—C31—H31A104.9 (14)
C8—C5—C6109.47 (6)C32—C31—H31A110.7 (13)
N3—C5—H5106.8 (10)O6—C31—H31B107.8 (13)
C8—C5—H5111.3 (11)C32—C31—H31B110.5 (12)
C6—C5—H5106.6 (11)H31A—C31—H31B111.1 (17)
O3—C6—O4125.01 (7)C31—C32—H32A109.5 (11)
O3—C6—C5119.36 (6)C31—C32—H32B112.5 (14)
O4—C6—C5115.58 (6)H32A—C32—H32B107.5 (17)
C1—C7—H7A111.0 (12)C31—C32—H32C109.0 (12)
C1—C7—H7B110.0 (13)H32A—C32—H32C111.6 (17)
H7A—C7—H7B107.4 (18)H32B—C32—H32C106.7 (19)
C1—C7—H7C111.0 (10)
C3—N2—C2—O11.18 (11)C8—C5—C6—O3115.71 (8)
C3—N2—C2—C1177.49 (6)N3—C5—C6—O4174.91 (6)
N1—C1—C2—O133.98 (9)C8—C5—C6—O461.83 (9)
C7—C1—C2—O186.55 (8)N2—C3—C20—C2162.90 (7)
N1—C1—C2—N2147.31 (6)C4—C3—C20—C2156.95 (7)
C7—C1—C2—N292.17 (8)C3—C20—C21—C2289.00 (8)
C2—N2—C3—C4166.37 (6)C3—C20—C21—C2689.50 (8)
C2—N2—C3—C2072.11 (8)C26—C21—C22—C231.76 (11)
C5—N3—C4—O24.73 (11)C20—C21—C22—C23176.78 (7)
C5—N3—C4—C3172.63 (6)C21—C22—C23—C240.35 (11)
N2—C3—C4—O225.65 (9)C22—C23—C24—O5176.68 (7)
C20—C3—C4—O297.22 (8)C22—C23—C24—C252.55 (11)
N2—C3—C4—N3156.88 (6)O5—C24—C25—C26176.67 (7)
C20—C3—C4—N380.25 (7)C23—C24—C25—C262.58 (11)
C4—N3—C5—C8129.52 (7)C24—C25—C26—C210.42 (11)
C4—N3—C5—C6108.07 (7)C22—C21—C26—C251.73 (11)
N3—C5—C6—O37.56 (9)C20—C21—C26—C25176.79 (7)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O5—H15···O6i0.81 (2)1.83 (2)2.627 (1)169 (2)
O6—H16···O3ii0.87 (3)1.82 (3)2.689 (1)176 (3)
N1—H11A···O4ii0.95 (2)1.85 (2)2.786 (1)170 (2)
N1—H11B···O5iii0.83 (2)2.04 (2)2.873 (1)174 (2)
N1—H11C···O2iv0.80 (2)1.95 (2)2.748 (1)178 (2)
N2—H12···O1v0.85 (2)2.18 (2)2.975 (1)156 (2)
N3—H13···O4vi0.85 (1)2.13 (1)2.963 (1)167 (2)
Symmetry codes: (i) x, y1/2, z+1; (ii) x, y, z1; (iii) x, y+1/2, z+1; (iv) x+1, y+1/2, z+1; (v) x+1, y1/2, z+1; (vi) x+1, y+1/2, z+2.

Experimental details

(I)(II)
Crystal data
Chemical formulaC15H21N3O5·2.628H2OC15H21N3O5·C2H6O
Mr370.69369.42
Crystal system, space groupMonoclinic, P21Monoclinic, P21
Temperature (K)920
a, b, c (Å)8.121 (3), 9.299 (4), 12.532 (5)8.845 (2), 9.057 (2), 12.364 (3)
β (°) 91.21 (2) 94.56 (3)
V3)946.2 (7)987.3 (4)
Z22
Radiation typeSynchrotron, λ = 0.50 ÅMo Kα
µ (mm1)0.060.09
Crystal size (mm)0.54 × 0.25 × 0.130.4 × 0.25 × 0.2
Data collection
DiffractometerHuber
diffractometer with MarCCD detector
Huber four-circle
diffractometer with Bruker SMART Apex CCD area-detector
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
9540, 5019, 4945 9710, 5258, 5178
Rint0.0440.035
(sin θ/λ)max1)0.8450.847
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.024, 0.068, 1.11 0.029, 0.077, 1.10
No. of reflections50195258
No. of parameters344343
No. of restraints12
H-atom treatmentAll H-atom parameters refinedAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.45, 0.240.50, 0.19
Absolute structureRmRm

Computer programs: MarCCD (Paulmann & Morgenroth, 2006), SMART (Bruker, 1997–2001), XDS (Kabsch, 1993), SMART, XDS, SAINT (Bruker, 1997–2001) and SADABS (Bruker, 1997–2001), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), PLATON (Spek, 2003), PLATON.

Selected geometric parameters (Å, º) for (I) top
O1—C21.2442 (9)N3—C51.4598 (9)
O2—C41.2444 (9)C1—C71.5283 (11)
O3—C61.2568 (9)C1—C21.5322 (9)
O4—C61.2859 (8)C3—C41.5322 (9)
O5—C241.3840 (10)C3—C201.5595 (11)
N1—C11.4971 (9)C5—C81.5381 (10)
N2—C21.3434 (9)C5—C61.5466 (10)
N2—C31.4622 (9)C20—C211.5135 (10)
N3—C41.3463 (9)
C2—N2—C3120.41 (6)N3—C4—C3114.97 (6)
C4—N3—C5121.63 (6)N3—C5—C6113.04 (6)
N1—C1—C2107.77 (5)O3—C6—C5120.53 (6)
N2—C2—C1115.60 (6)O4—C6—C5114.91 (6)
N2—C3—C4108.28 (5)
Hydrogen-bond geometry (Å, º) for (I) top
D—H···AD—HH···AD···AD—H···A
O5—H15···O7i0.86 (2)1.79 (2)2.629 (1)165 (2)
O6—H61···O30.84 (2)2.02 (2)2.847 (1)172 (2)
O6—H62···O4ii0.89 (2)1.93 (3)2.821 (1)176 (2)
O7—H71···O3iii0.86 (2)1.90 (2)2.746 (1)173 (2)
O7—H72···O60.80 (2)1.97 (2)2.771 (1)175 (3)
O8—H81···O70.80 (4)2.12 (4)2.916 (1)173 (4)
N1—H11A···O4iv0.96 (2)1.88 (2)2.827 (1)175 (2)
N1—H11B···O5v0.88 (2)1.91 (2)2.792 (1)174 (2)
N1—H11C···O2vi0.88 (2)1.97 (2)2.821 (1)163 (2)
N2—H12···O1vii0.88 (2)2.10 (2)2.947 (2)160 (2)
N3—H13···O4ii0.82 (2)2.21 (2)3.028 (2)172 (2)
Symmetry codes: (i) x, y+1, z; (ii) x, y1/2, z+2; (iii) x+1, y1/2, z+2; (iv) x, y, z1; (v) x+1, y1/2, z+1; (vi) x, y1/2, z+1; (vii) x, y+1/2, z+1.
Selected geometric parameters (Å, º) for (II) top
O1—C21.2434 (9)N3—C51.4627 (9)
O2—C41.2457 (9)C1—C21.5293 (10)
O3—C61.2594 (9)C1—C71.5344 (11)
O4—C61.2811 (9)C3—C41.5331 (10)
O5—C241.3809 (10)C3—C201.5635 (10)
N1—C11.4993 (10)C5—C81.5382 (11)
N2—C21.3451 (9)C5—C61.5448 (10)
N2—C31.4612 (9)C20—C211.5142 (10)
N3—C41.3399 (9)
C2—N2—C3121.87 (6)N3—C4—C3115.88 (6)
C4—N3—C5122.22 (6)N3—C5—C6111.62 (6)
N1—C1—C2108.19 (6)O3—C6—C5119.36 (6)
N2—C2—C1115.64 (6)O4—C6—C5115.58 (6)
N2—C3—C4107.40 (6)
Hydrogen-bond geometry (Å, º) for (II) top
D—H···AD—HH···AD···AD—H···A
O5—H15···O6i0.81 (2)1.83 (2)2.627 (1)169 (2)
O6—H16···O3ii0.87 (3)1.82 (3)2.689 (1)176 (3)
N1—H11A···O4ii0.95 (2)1.85 (2)2.786 (1)170 (2)
N1—H11B···O5iii0.83 (2)2.04 (2)2.873 (1)174 (2)
N1—H11C···O2iv0.80 (2)1.95 (2)2.748 (1)178 (2)
N2—H12···O1v0.85 (2)2.18 (2)2.975 (1)156 (2)
N3—H13···O4vi0.85 (1)2.13 (1)2.963 (1)167 (2)
Symmetry codes: (i) x, y1/2, z+1; (ii) x, y, z1; (iii) x, y+1/2, z+1; (iv) x+1, y+1/2, z+1; (v) x+1, y1/2, z+1; (vi) x+1, y+1/2, z+2.
A comparison of torsion angles (°) describing the conformation of the main chain of tripeptides Ala-Xxx-Ala. ψ, ω and ϕ are defined in agreement with IUPAC–IUB Commission on Biochemical Nomenclature (1970). top
Torsion angleSymbol(I)a(II)aAAAbAAAbAGAcAGAd
N1—C1—C2—N2ψ1155.20 (5)147.31 (6)152.7 (3)162.2 (3)-146.8 (2)172.6 (2)
C1—C2—N2—C3ω1178.39 (5)177.49 (6)175.2 (3)-179.2 (3)-173.5 (2)-178.2 (2)
C2—N2—C3—C4ϕ2-156.19 (5)-166.37 (6)-145.7 (3)-156.2 (3)86.4 (2)91.7 (1)
N2—C3—C4—N3ψ2147.39 (5)156.88 (6)145.5 (3)149.9 (3)-167.4 (2)-151.9 (2)
C3—C4—N3—C5ω2-179.08 (5)172.63 (6)176.6 (3)173.0 (3)-173.8 (2)-176.9 (1)
C4—N3—C5—C6ϕ3-90.75 (7)-108.07 (7)-147.0 (3)-159.9 (3)-159.1 (2)-71.3 (2)
N3—C5—C6—O3ψ3,1-7.41 (8)-7.56 (9)-9.7 (3)-10.1 (3)-5.0 (3)-6.9 (1)
N3—C5—C6—O4ψ3,2174.16 (5)174.91 (6)172.3 (3)143.9 (3)176.9 (3)172.4 (2)
C4—N3—C5—C8145.72 (6)129.52 (7)--
Notes: (a) this work; (b) L-alanyl-L-alanyl-L-alanine hemihydrate (Rödel et al., 2006); (c) L-alanylglycyl-L-alanine monohydrate (Förster et al., 2005); (d) L-alanylglycyl-L-alanine (Padiyar & Seshadri, 1996).
 

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