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

The A1 subunit of the carotenoprotein alpha-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 A. The crystals are stable to radiation. The space group of the crystals is P2(1)2(1)2(1). The unit-cell parameters are a = 41.9, b = 80.7, c = 110.8 A. '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.