Purification and characterization of a thermostable pyruvate kinase from the actinomycete Microbispora thermodiastatica

The pyruvate kinase of Microbispora thermodiastatica was purified to homogeneity and some properties of the enzyme were characterized. The molecular weight of the enzyme by gel filtration is 277,000. The subunit molecular weight is 55,000 by SDS-polyacrylamide gel electrophoresis, and only one N-terminal amino acid sequence was obtained. It had a pH optimum around pH 4.5 to 7.0 and was stable over the range of pH 4.0-8.0, The enzyme is thermostable and no activity was lost after heat treatment at 55 degrees C for 60 min. AMP activated this enzyme and the saturation curve of the enzyme for PEP changed from sigmoidal type to hyperbolic type in the presence of AMP.