S-ADENOSYLMETHIONINE DECARBOXYLASE FROM THE THERMOPHILIC ARCHAEBACTERIUM SULFOLOBUS-SOLFATARICUS - PURIFICATION, MOLECULAR-PROPERTIES AND STUDIES ON THE COVALENTLY BOUND PYRUVATE

S-Adenosylmethionine decarboxylase from Sulfolobus solfataricus, a thermoacidophilic archaebacterium optimally growing at 87-degrees-C, has been purified to homogeneity. The specific activity of the homogeneous enzyme is 12 nmol CO2 formed min-1 (mg protein)-1 and the overall yield 8%. The enzyme is thermophilic with an optimum at 75-degrees-C, is thermostable, and does not require divalent cations or putrescine for activity. It has a molecular mass of 32 kDa, and appears to be a monomeric protein. S-Adenosylmethionine decarboxylase from S. solfataricus contains covalently linked pyruvate as prosthetic group and is inactivated in a time-dependent process by NaCNBH3, in the presence of both the substrate and the product. Incubation with decarboxylated S-adenosyl[Me-H-3]methionine and NaCNBH3 resulted in the labeling of the protein at the active site.