Uridine galactose 4-epimerase

UDPGal = UDPG Uridine diphosphate galactose 4-epimerase... 

Seyama, Y., Kalckar, H. M. Specific tritium labeling of uridine diphosphogalactose 4-epimerase by d-1-3H Galactose. Biochemistry 11, 36—39 (1972). 

Wee, T. G., Frey, P. A. Studies on the mechanism of action of uridine diphosphate galactose 4-epimerase. Substate dependent reduction by sodium borohydride. J. Biol. Chem. 248, 33—40 (1973). 

Ketley, J. N., Schellenberg, K. A. Substrate stereochemical requirements in the reductive inactivation of uridine diphosphate galactose 4-epimerase by sugar and 5 -uridine monophosphate. Biochemistry 12, 315—320 (1973). 

UDP-galactose can be converted to UDP-glucose by uridine diphosphogalac-tose 4-epimerase. 

Fermentation procedures useful for the production of uridine 5 -(a-D-galactopyranosyl pyrophosphate) involve the cultivation of bacterial mutant-strains that are deficient in the 4"-epimerase for 30 (see Section V,l,b, p. 369) in D-galactose-containing media,245-247 or by incubating Torulopsis Candida cells with uridine 5 -phosphate, D-galactose, potassium phosphate, and magnesium sulfate.248... 

It contains the attenuated strain Ty21a of Salmonella typhi. The attenuation is due to the absence of enzyme uridine diphosphate galactose-4-epimerase which is essential for the production of the lipopolysaccharide O antigen. The absence of this enzyme makes Ty21a highly immunogenic. 

Bergren WR, Ng WG, Donnel GN (1973) Uridine diphosphate galactose-4-epimerase in human and other mammalian haemolysates. Biochim Biophys Acta 313 464-472... 

Gitzelmann R, Steinmann B, Mitchell B, Haigis E (1976) Uridine diphosphate galactose 4 -epimerase deficiency. IV. Report of eight cases in three families. HelvPaediatr Acta 31 441-452... 

Ng WG, Donnel GN, Hodgman JE, Bergren WR (1967) Differences in uridine diphosphate galactose-4-epimerase between haemolysates of newborns and of adults. Nature 214 283-284... 

This over-all scheme has so far been detected in animal liver and in micro-organisms. Certain yeasts can adapt themselves to utilizing D-galactose, and this adaptation has been variously attributed to the development of galactokinase, of a-D-galactosyl uridyl transferase, and of both of these enzymes and uridine 5-(i>-galactosyl pyrophosphate) 4-epimerase. ... 

Fig. 20.5 The Leloir pathway of galactose metabolism and the uridine diphosphate (UDP) glucose pyrophosphorylase pathway. Gaik, galactokinase gait, galactose 1-phosphate uridyltrans-ferase gale, UDP-galactose 4-epimerase hex, hexokinase pgm, phosphoglucomutase Ugp, UDP-glucose pyrophosphorylase...

Figure 13.1 Lactose metabolism in lactic acid bacteria. GalK, galactokinase GalT, galactose-l-phosphate uridyltransferase GalE, UDP-galactose-4 -epimerase GalU, glucose-l-phosphate uridyltransferase UPD, uridine diphosphate.

The isomerases catalyse intramolecular rearrangement in optical and positional isomers. Typical of this class are the epimerases, such as uridine diphosphate glucose 4-epimerase. This enzyme catalyses the change of configiu tion at the fourth carbon atom of glucose, and galactose is produced (see Chapter 9). The group includes ... 

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