Apocrustacyanin A1 from the lobster carotenoprotein α-crustacyanin: crystallization and initial X-ray analysis involving softer X-rays

The A1 subunit of the carotenoprotein α-crustacyanin, isolated from lobster carapace, has been crystallized using the vapour-diffusion method. The crystals, grown in solutions of ammonium sulfate containing methylpentanediol (MPD), diffracted to 2.0 Å. The crystals are stable to radiation. The space group of the crystals is P2₁2₁2₁. The unit-cell parameters are a = 41.9, b = 80.7, c = 110.8 Å. `Standard structure determination' has been unsuccessful within this crustacyanin family. Instead, an approach based on the S atoms is being undertaken involving softer X-rays at the SRS, Daresbury.