Crystalline 3-phospho-d-glycerate kinase from horse muscle

Phosphoglycerate kinase has been isolated in crystalline form from horse muscle. A convenient isolation procedure is described that yields homogeneous enzyme of specific activity 700 units/mg (30 degrees C). The enzyme is monomeric, and has a molecular weight 47 000. Of the eight cysteine residues in the protein, two react rapidly with Nbs21 with the concomitant loss of the catalytic activity. Since the isolation of phosphoglycerate kinase from yeast (Bücher, 1955) there have been several reports of purification methods yielding enzyme approaching molecular homogeneity, from rabbit muscle (Beisenherz et al., 1953; Czok and Bücher, 1960; Rao and Oesper, 1961; Avramov and Repin, 1965; and Scopes, 1969) and from chicken muscle (Gosselin-Rey, 1965). Crystalline material has been isolated from human erythrocytes (Hashimoto and Yoshikawa, 1962), and from yeast and rabbit muscle (Krietsch and Bücher, 1970). Cystallographic work on phosphoglycerate kinase from horse muscle by Blake et al. (1972) and Blake and Evans (1974) has prompted mechanistic interest in the enzyme, and we report here a simplified isolation procedure and some properties of the crystalline material from this source.