Open AccessGanglioside biosynthesis in rat liver
Author(s) -
BUSAM Klaus,
DECKER Karl
Publication year - 1986
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1986.tb09934.x
Subject(s) - lactosylceramide , sialyltransferase , biosynthesis , ganglioside , biochemistry , glycolipid , enzyme , atp synthase , chemistry , neuraminic acid , golgi apparatus , sialic acid , endoplasmic reticulum
Three sialyltransferase activities involved in ganglioside biosynthesis were studied in Golgi‐enriched preparations of rat liver: the formation of G M3 , G D3 and G D1a . The conditions for the quantitative assays of these enzymatic reactions were standardized and optimized, with Triton X‐100 being used as detergent. The apparent K m values of each sialyltransferase for N ‐acetyl‐2‐(5′‐cytidylyl)neuraminic acid (1.5 mM with G M3 synthase, 0.2 mM with G D3 synthase, and 0.5 mM with G D1a synthase) and the respective glycolipid substrates (0.08 mM for lactosylceramide, 0.1 mM for G M3 , and 0.5 mM for G M1 ) were determined. Competition experiments showed that the three sialyltransferase activities are three individual catalytic entities. Moreover, evidence was found that product inhibition may play a role in the regulation of the activity of sialyltransferases.