Crystallization and preliminary analysis of enzyme-substrate complexes of pyruvate kinase from rabbit muscle

Abstract

Pyruvate kinase from rabbit muscle has been crystallized in a form suitable for high resolution X-ray analysis. Complexes of the enzyme with Mn2+ and either pyruvate or oxalate crystallize from solutions of polyethyl-eneglycol 8000 at pH 6.0. Crystals obtained from solutions of the complexes with pyruvate or oxalate appear isomorphous and belong to the triclinic space group P1. The crystals have unit cell dimensions a = 83.3(4) A, b = 109.4(6) A, c = 145.7 (7) A, alpha = 94.9 degrees, beta = 93.6 degrees, gamma = 112.2 degrees. These crystals diffract to better than 2.4 A resolution and are stable in the X-ray beam for at least 20 hr. Electron paramagnetic resonance measurements on a single crystal show that Mn2+ is bound to the crystalline protein.