Glutamate Decarboxylase: Preliminary Crystallographic Data

Summary

Glutamate decarboxylase was purified from Escherichia coli and crystallized by vapour diffusion and microdialysis techniques in the presence of polyethylene glycol. Growth of large crystals suitable for X-ray studies is particularly favoured by low concentrations of citric or glutaric acid, which are both effective inhibitors of the enzyme. Inhibitor binding must induce the conformational changes that are essential for crystal nucleation since no crystallization occurred with non-inhibitory buffers of similar ionic composition. The crystals, of space group R3, diffract to a resolution of 2.9 Ȧ. The dimensions of the rhombohedral unit cell are a = b = c = 116 Ȧ, α= β = γ =116° with a dimer in the asymmetric unit. The equivalent hexagonal cell has a = b = 199 Ȧ, c = 69 Ȧ, α= β = 90°, γ= 120°.