Of uridine diphosphate-galactose

Most nucleotide sugars are formed in the cytosol, generally from reactions involving the corresponding nucleoside triphosphate. GMP-sialic acids are formed in the nucleus. Formation of uridine diphosphate galactose (UDP-Gal) requires the following two reactions in mammahan tissues ... 

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). 

Kuhn, N. J. and White, A. 1976. Evidence for specific transport of uridine diphosphate galactose across the Golgi membrane of rat mammary gland. Biochem. J. 154, 243-244. 

H14. Helting, T., Biosynthesis of heparin. Solubilisation, partial separation, and purification of uridine diphosphate-galactose acceptor galactosyltransferases from mouse mastocytoma.. Biol. Chem. 246, 815-822 (1971). 

L2. Leloir, L. F., The enzymatic transformation of uridine diphosphate glucose into a galactose derivative. Arch. Biochem. Biophys. 33, 186-190 (1951). 

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. 

Uridine diphosphate galactose 4-epimerase Galactosemia with additional findings of hypotonia and nerve deafness... 

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... 

Uridine diphosphate galactose (109) was prepared using seven enzymes involved in three biosynthetic pathways, immobilised on super-bead columns. This method, which converted 50% of uracyl monophosphate into UDP-galactose (109), was superior to the solution approach as enzyme stability was improved. To study the biosynthesis of the pseudosaccaharide acarbose, thymidine 5 -diphospho-4-amino-4,6-dideoxy-a-D-glucopyranose(110) was synthesised from galactose in sixteen steps. 

Under appropriate experimental conditions, the blood type of red blood cells can be changed by addition or removal of specific carbohydrate residues. For example, when type O red blood cells are incubated with the galactose donor substrate (uridine diphosphate galactose) and the specific a-galactosyltransferase enzyme, they are... 

Leloir, L.F. (1951) The Enzymic Transformation of Uridine Diphosphate into a Galactose Derivative , Archives of Biochemistry and Biophysics, 33, 186-90 Leloir, L.F., Staneloni, R.J., Carminatti, H. Behrens, N.H. (1973) Biosynthesis of a N,N-diacetylchitobiose Containing lipid by Liver Microsomes. Probable Dolichol Phosphate Derivative , Biochemical and Biophysical Research Communications, 52, 1285-92... 

L. is the most important carbohydrate in the milk of all mammals. Human milk contains 6-8%, cow s milk 4-5%. L. is a component of a few oligosaccharides, and also occurs in plants, e.g. in fruits and pollen. In L. synthesis in the milk glands of mammals, the galactose residue of uridine diphosphate p-galac-tose is transferred and linked to the OH on C4 of d-glucose, a process catalysed by lactose synthetase,... 

Enzymatic synthesis of uridine diphosphate glucose has been observed, but there are no published reports on how the synthesis takes place. However, we do have some indication of how the compound may act as a coenzyme. When incubated with an extract of S. fragilis it is transformed into uridine diphosphate galactose. This would be a biological Walden inversion. Discovery of this reaction has led to the following hypothesis for the mechanism of the conversion of galactose-1-phosphate to glucose-l-phosphate ... 

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