Date of Award:

5-1971

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biology

Committee Chair(s)

Carl A. Westby

Committee

Carl A. Westby

Committee

Bruce F. Burnham

Committee

Rex S. Spendlove

Abstract

Ribose-5 '-phosphate aminotransferase, an alternate first enzyme in the purine de novo pathway, has been purified about 800-fold from Salmonella typhimurium (pur D-55 ). The enzyme is distinct from ribosylpyrophosphate-5'-phosphate amidotransferase (E C 2.4.2.14), has an approximate molecular weight of 229,000, and requires ribose-5'-phosphate, ATP and either ammonium ion, carbamyl phosphate or L-glutamine, to synthesize 5'-phosphoribosylamine (PRA). A coupled assay system, employing a S. typhimurium (pur G-310) extract as the coupling-agent source, was used to measure the enzyme. PRA production in this system was inhibited by higher ribose-5' -phosphate concentrations and longer (over 10 minutes) incubation periods. It is proposed that an alternate pathway for the initial step of purine biosynthesis exists in S. typhimurium, namely, the direct conversion of ribose-5 '-phosphate and ammonium ion to PRA.

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Included in

Biology Commons

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