UDP-D-galactose

Phase 2. Recruitment and conversion of an NDP-activated and neutral hex-ose from primary metabolism this is most likely UDP-D-glucose, which by the action of an UDP-glucose 4-epimerase, either the HygJ or HygK protein, respectively, becomes converted into the suggested precursor UDP-D-galactose. 

Scheme 1.—A Possible Pathway for the Formation of UDP-D-Galactose (U = Uridin-5 -yl).

D-Galactose + ATP a-D-galactosyl phosphate + ADP a-D-Galactosyl phosphate + UTP UDP-D-galactose + PPi... 

In the second route, UDP-D-galactose may be synthesized by the action of UTP-a-D-galactosyl phosphate uridyltransferase on UDP-D-glucose and a-D-galactosyl phosphate here, an exchange reaction takes place. 

In addition to UDP-D-galactose, other D-galactosyl esters of nucleotides, such as TDP-D-galactose from mung beans 23 and GDP-D-galac-tose from strawberries,24 have been identified as intermediates. These derivatives also play a role as D-galactosyl donors. 

By in vitro experiments, Hopf and Kandler 1 580 showed that an enzyme preparation from the leaves of A. podagraria is able to synthesize umbelliferose when it is incubated with UDP-D-galactose and sucrose. 

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