Purification, crystallization and preliminary crystallographic analysis of the marine α-amylase AmyP.

AmyP is a raw-starch-degrading α-amylase newly identified from a marine metagenome library. It shares low sequence similarity with characterized glycoside hydrolases and was classified into a new subfamily of GH13. In particular, it showed preferential degradation to raw rice starch. Full-length AmyP was cloned and overexpressed in Escherichia coli, then purified and crystallized in the presence of its substrate analogue β-cyclodextrin. X-ray diffraction data were collected to a resolution of 2.1 Å. The crystal belonged to space group P2₁2₁2, with unit-cell parameters a=129.824, b=215.534, c=79.699 Å, α=β=γ=90°, and was estimated to contain two molecules in one asymmetric unit.