Affordable Access

Purification and characterization of Escherichia coli xanthine-guanine phosphoribosyltransferase produced by plasmid pSV2gpt.

Authors
Type
Published Article
Journal
Biochimica et Biophysica Acta
0006-3002
Publisher
Elsevier
Publication Date
Volume
839
Issue
3
Pages
233–239
Identifiers
PMID: 3886014
Source
Medline

Abstract

The enzyme xanthine-guanine phosphoribosyltransferase from Escherichia coli cells harboring the plasmid pSV2gpt has been purified 30-fold to near homogeneity by single-step GMP-agarose affinity chromatography. It has a Km value of 2.5, 42 and 182 microM for the substrates guanine, xanthine and hypoxanthine, respectively, with guanine being the most preferred substrate. The enzyme exhibits a Km value of 38.5 microM for PRib-PP with guanine as second substrate and of 100 microM when xanthine is used as the second substrate. It is markedly inhibited by 6-thioguanine, GMP and to a lesser extent by some other purine analogues. Thioguanine has been found to be the most potent inhibitor. The subunit molecular weight of xanthine-guanine phosphoribosyltransferase was determined to be 19 000. The in situ activity assay on a nondenaturing polyacrylamide gel electrophoresis gel has indicated that a second E. coli phosphoribosyltransferase preferentially uses hypoxanthine as opposed to guanine as a substrate, and it does not use xanthine.

There are no comments yet on this publication. Be the first to share your thoughts.

Statistics

Seen <100 times
0 Comments