Abstract
A radioassay has been developed for the bifunctional enzyme, AICAR transformylase-IMP cyclohydrolase, which catalyzes reactions 9 and 10 of the de novo pathway for biosynthesis of purine nucleotides (AICAR-->FAICAR-->IMP). 3H-labeled AICAR or FAICAR is converted enzymically to product(s) which are separated by one-dimensional thin-layer chromatography prior to quantification by scintillation counting. Using this sensitive radioassay, a dissociation constant of IMP cyclohydrolase for FAICAR of 0.87 microM has been determined and AICAR, FAICAR, and IMP can be quantified in assay mixtures for AICAR transformylase-IMP cyclohydrolase. The ratio of specific enzymic activities for AICAR transformylase:IMP cyclohydrolase is 1:44.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Acyltransferases / analysis*
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Aminoimidazole Carboxamide / analogs & derivatives
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Aminoimidazole Carboxamide / chemical synthesis
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Aminoimidazole Carboxamide / metabolism
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Chromatography, Thin Layer / methods
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Hydroxymethyl and Formyl Transferases*
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Indicators and Reagents
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Inosine Monophosphate / metabolism
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Kinetics
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Nucleotide Deaminases / analysis*
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Phosphoribosylaminoimidazolecarboxamide Formyltransferase
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Phosphorylation
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Phosphotransferases
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Radioisotope Dilution Technique
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Ribonucleosides
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Ribonucleotides / chemical synthesis
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Ribonucleotides / metabolism
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Sensitivity and Specificity
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Serratia marcescens / enzymology
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Time Factors
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Tritium
Substances
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Indicators and Reagents
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Ribonucleosides
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Ribonucleotides
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Tritium
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5-formamidoimidazole-4-carboxamide ribotide
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Inosine Monophosphate
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Aminoimidazole Carboxamide
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acadesine
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Hydroxymethyl and Formyl Transferases
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Phosphoribosylaminoimidazolecarboxamide Formyltransferase
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Acyltransferases
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Phosphotransferases
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nucleoside phosphotransferase
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Nucleotide Deaminases
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IMP cyclohydrolase
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AICA ribonucleotide