Two forms of pyruvate kinase in Escherichia coli. A comparison of chemical and molecular properties

The two forms of pyruvate kinase (ATP:pyruvate 2-O-phosphotransferase, EC 2.7.1.40) present in Escherichia coli have been purified from the same cultures and crystallized. A modified procedure for the purification of type I pyruvate kinase is described. Molecular weight, subunit structure, amino acid composition, NH2-terminal amino acid, maps of tryptic peptides and conditions for crystallization have been determined for the two forms. A comparison of these data shows that the two forms are different proteins, each being a tetramer of identical subunits.