Purine Nucleoside Phosphorylase from Human Erythrocytes

Purified purine nucleoside phosphorylase (purine riboside: orthophosphate ribosyltransferase, EC 2.4.2.1) from human erythrocytes has been subjected to a kinetic analysis, including initial velocity and product inhibition studies. No evidence was seen for a "ping-pong," or shuttle, mechani...

Full description

Saved in:
Bibliographic Details
Published in:The Journal of biological chemistry 1968-04, Vol.243 (8), p.1771-1776
Main Authors: Kim, B K, Cha, S, Parks, R E
Format: Article
Language:English
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Purified purine nucleoside phosphorylase (purine riboside: orthophosphate ribosyltransferase, EC 2.4.2.1) from human erythrocytes has been subjected to a kinetic analysis, including initial velocity and product inhibition studies. No evidence was seen for a "ping-pong," or shuttle, mechanism, which indicates that a ribosylated or phosphorylated enzyme is not an obligatory intermediate in the reaction mechanism. The results of the kinetic analysis are consistent with the predominant mechanism being an "ordered Bi-Bi reaction," with the nucleoside the first substrate to add to, and the purine base the last product to leave, the enzyme surface. The binding of isotopically labeled substrates to the enzyme has been examined. No evidence was obtained to indicate the formation of a ribosylated enzyme or the formation of a tight complex of orthophosphate or of ribose 1-phosphate with the enzyme.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(18)93510-6