ISSN:
0749-503X
Keywords:
L-Arabinose
;
D-xylose
;
UDP-glucose 4-epimerase
;
inactivation
;
Saccharomyces
;
Life and Medical Sciences
;
Genetics
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
Notes:
In a previous paper (Cármenes et al., 1984) we reported that UDP-glucose 4-epimerase from Saccharomyces was inactivated both in vitro (Crude extracts) by L-arabinose or D-xylose. In this paper, we reported that pure epimerase requires the presence of UMP or UDP to be inactivated by sugars and that the inactivation is due to the reduction of the epimerase NAD+, which is essential for epimerase activity. The inactivation rate is directly proportional to epimerase and sugar concentrations and hyperbolically proportional to UMP concentration. In situ experiments made with permeabilized cells showed that epimerase is inactivated in the same way when it is inside the cell. In vivo studies showed that epimerase is inactivated to a smaller extent when 1% Dgalactose is present in the culture medium than when 1% ethanol is the main carbon source.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/yea.320020205
