Crystals of a trypsin-modified alkaline phosphatase. Preliminary crystallographic characterization.

Trypsin-modified alkaline phosphatase from Escherichia coli has been crystallized in a form distinct from the two known crystal forms of the native enzyme. The large well diffracting crystals belong to the orthorhombic space group P2(1)2(1)2(1), possess unit cell dimensions a = 56.0 A, b = 136.0 A, c = 283.9 A with 2 dimers per asymmetric unit, and are suitable for high resolution x-ray crystallographic studies. The observed structural and functional differences between the native and modified molecules are a result of peptide bond cleavage at Arg10-Ala11 with loss of the NH2-terminal decapeptide in both subunits of the dimer.