Affiliation:
1. Department of Biological Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
Abstract
Fructose was oxidized and converted to cellulose by cells of
Acetobacter xylinum
grown on fructose or succinate, but not by cells grown on glucose. In resting fructose-grown cells, glucose strongly suppressed fructose utilization. Extracts obtained from fructose- or succinate-grown cells catalyzed the adenosine triphosphate (ATP)-dependent formation of the 6-phosphate esters of glucose and fructose, whereas glucose-grown cell extracts phosphorylated glucose but not fructose. Fructokinase and glucokinase activities were separated and partially purified from cells grown on glucose, fructose, or succinate. Whereas fructokinase phosphorylated fructose only, glucokinase was active towards glucose and less active towards mannose and glucosamine. The optimal
p
H for the fructokinase was 7.4 and for the glucokinase was 8.5. The
K
m
values for the fructokinase were: fructose, 6.2 m
m
; and ATP, 0.83 m
m
. The
K
m
values for the glucokinase were: glucose, 0.22 m
m
; and ATP, 4.2 m
m
. Fructokinase was inhibited by glucose, glucosamine, mannose, and deoxyglucose in a manner competitive with respect to fructose, with
K
i
values of 0.1, 0.14, 0.5, and 7.5 m
m
, respectively. Adenosine diphosphate (ADP) and adenosine monophosphate (AMP) inhibited both kinases noncompetitively with respect to ATP. The
K
i
values were: 1.8 m
m
(ADP) and 2.1 m
m
(AMP) for fructokinase, and 2.2 m
m
(ADP) and 9.6 m
m
(AMP) for glucokinase. Fructose metabolism in
A. xylinum
appears to be regulated by the synthesis and activity of fructokinase.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
29 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