Journal of Applied Crystallography

Volume 34, Part 4 (August 2001)

research papers

J. Appl. Cryst. (2001). 34, 454-457 [ doi:10.1107/S0021889801007245 ]

Neutron Laue diffraction experiments on a large unit cell: concanavalin A complexed with methyl--D-glucopyranoside

A. J. Kalb (Gilboa), D. A. A. Myles, J. Habash, J. Raftery and J. R. Helliwell

Abstract: A neutron Laue diffraction experiment on a complex of concanavalin A with methyl- [alpha] -D-glucopyranoside extensively soaked in D₂O (space group I2₁3, a = 167.8 Å), which resulted in 3.5 Å diffraction data, is described. In a programme of structural studies of crystalline saccharide complexes of concanavalin A, the unit cell of the cubic I2₁3 complex of concanavalin A with methyl- [alpha] -D-glucopyranoside is one of the largest. With its cell edge of 167.8 Å and its asymmetric unit of molecular weight 50 kDa, it represents a challenge for current neutron diffraction technology. The size of the crystal used in this experiment, although large (4 × 3 × 2 mm), was not the largest ever produced for this complex. The degree of spatial overlapping observed in the Laue experiment, however, suggests that use of larger crystals would be a disadvantage. On the basis of these observations, several technical improvements for macromolecular neutron crystallography are suggested.

Keywords: neutron diffraction; Laue diffraction; concanavalin A; methyl--D-glucopyranoside; protein crystallography; macromolecular crystallography; data collection.