Crystallization and initial X-ray analysis of β-crustacyanin, the dimer of apoproteins A₂ and C₁, each with a bound astaxanthin molecule

Crystals of β-crustacyanin, a carotenoid-binding protein from lobster carapace, have been grown under oil from solutions containing sodium potassium phosphate as precipitant. They grow slowly over a period of months to reach maximal dimensions of 0.5 × 0.1 × 0.1 mm, and belong to space group P622 with cell dimensions: a = b = 124.39, c = 188.86 Å and γ = 120°. The crystals diffract to beyond 3 Å but are very radiation sensitive, limiting the resolution of usable data. The unit-cell volume suggests that there are two β-crustacyanin molecules per asymmetric unit.