Avian liver mevalonate 5-diphosphate decarboxylase: substrate and inhibitor activities of the phosphorothioate analogues of adenosine triphosphate.
The diastereoisomers of ATP alpha S and of ATP beta S have been used as substrate analogues for avian liver mevalonate 5-diphosphate decarboxylase. When the diastereoisomers of ATP alpha S were used, no reversal of the stereospecificity was seen upon changing Mg2+ for Cd2+, thus suggesting that the metal ion does not coordinate through the alpha-phosphoryl group of the nucleotide. Reversal of the stereospecificity, however, was observed when using the diastereoisomers of ATP beta S and upon changing Mg2+ by Zn2+ as the activating metal ion. Similar competitive inhibition constants for the diastereoisomers of MgATP beta S against MgATP were found. It is proposed that the active metal-nucleotide complex in catalysis is the lambda, beta-gamma MgATP complex.
Jabalquinto
A M
AM
Departamento de Química, Facultad de Ciencia, Universidad de Santiago de Chile.
Cardemil
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D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000737:chemistry; D000818:Animals; D002262:Carboxy-Lyases / Q000378:metabolism*; D002645:Chickens; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008968:Molecular Conformation; D013379:Substrate Specificity
D000255:Adenosine Triphosphate; D002262:Carboxy-Lyases