Crystallization and preliminary X‐ray analysis of outer membrane phospholipase A fromEscherichia coli

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Abstract
The outer membrane phospholipase A (OMPLA) of Escherichia coli is one of the few integral outer membrane proteins displaying enzymatic activity. It is encoded as a mature protein of 269 amino acids preceded by a signal sequence of 20 amino acids. There is no sequence homology with water-soluble lipases and phospholipases. Crystals of the mature enzyme were obtained at 22°C from 24–28% (vlv) 2-methyl-2,4-pentanediol in Bis-Tris buffer, pH 5.9–6.0, with 1 mM calcium chloride and 1.5% (w/v) β-octylglucoside. They have the symmetry of the trigonal spacegroup P3121 (or P3221) with cell dimensions of a = b = 79.6 Å and c = 102.8 Å (α = β = 90°, γ = 120°). Native crystals diffract to a resolution of 2.6 Å