Abstract
The oxidation of D-alanine, hypoxanthine and glucose by D-amino-acid oxidase, xanthine oxidase and glucose oxidase (notatin) respectively has been studied at O
2
tensions varying from 1 to 100 %, mainly with a view to examining enzyme activity at an O
2
tension comparable to that obtaining in the animal body, i.e. < 10 % O
2
. It was found that (
a
) the rate of substrate oxidation decreases markedly at O
2
tensions < 20 % , i.e. the enzymes examined have a low O
2
affinity; (
b
) the substrate concentration giving half-maximal oxidation rate (= Michaelis constant,
K
m
) decreases with a lowering of the O
2
tension; (
c
) the rate of primary substrate oxidation at low O
2
tension in presence of catalase is higher than in presence of catalase and a secondary substrate which undergoes peroxidatic oxidation by catalase and H
2
O
2
. A possible mechanism underlying this effect, which involves the participation of catalase and H
2
O
2
in primary substrate oxidation at low O
2
tension, is suggested.
Cited by
33 articles.
订阅此论文施引文献
订阅此论文施引文献，注册后可以免费订阅5篇论文的施引文献，订阅后可以查看论文全部施引文献