title: An alleged yeast polyphosphate kinase is actually diadenosine-5', 5"'-P1,P4-tetraphosphate alpha,beta-phosphorylase.
abstract: Polyphosphates are a major constituent of the yeast Saccharomyces cerevisiae. A purification of the enzyme polyphosphate kinase (E.C. 2.7.4.1) from this organism has been reported (Felter, S., and Stahl, A.J.C. (1973) Biochimie (Paris) 55, 245-251). The assay for activity used in this purification was the production of 32P-labeled nucleotide, presumed to be ATP, in the presence of [32P]polyphosphate and ADP. We have found that this assay does not reflect the activity of a polyphosphate kinase but rather the combination of an exopolyphosphatase, releasing free [32P]phosphate from the added [32P]polyphosphate, and the ADP-[32P]phosphate exchange activity of the enzyme diadenosine 5',5"'-P1, P4-tetraphosphate alpha, beta-phosphorylase (Ap4A phosphorylase). We also present direct evidence for the formation of an enzyme-AMP intermediate in the actin of Ap4A phosphorylase.
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
authors.forename: J W
authors.initials: JW
authors.lastname: Booth
authors.forename: G
authors.initials: G
authors.lastname: Guidotti
mesh_terms: D000249:Adenosine Monophosphate / Q000378:metabolism; D009713:Nucleotidyltransferases / Q000302:isolation & purification / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D010710:Phosphates; D000249:Adenosine Monophosphate; D009713:Nucleotidyltransferases; C044740:diadenosine 5,5'''-P(1),P(4)-tetraphosphate alpha,beta-phosphorylase