Crystallization and preliminary crystallographic characterization of aspartic proteinase-A from baker's yeast and its complexes with inhibitors.

The aspartic proteinase from yeast vacuoles, proteinase-A, has been crystallized with and without non-hydrolysable transition-state analogue inhibitors. The native enzyme crystals belong to the space group I2(1)2(1)2(1), with two molecules per asymmetric unit. The inhibitor complex crystals are trigonal with space group P3(2)21 and with one molecule in the asymmetric unit. Preliminary X-ray analysis of both native enzyme and its complexes indicate that the complexes diffract to higher resolution than the native crystals. This is probably due to reduced flexibility in the enzyme-inhibitor complex.