Biosynthesis of lipid-linked oligosaccharides in embryonic liver formation of dolichyl pyrophosphate N-acetylglucosaminyl intermediates

Abstract

1. 1. Liver microsomes from pig embryos synthesized dolichyl pyrophosphate N-acetylglucosamine and converted it to dolichyl pyrophosphate N, N′-diacetylchitobiose. 2. 2. N-acetylglucosaminyl transferase activity towards dolichol was about 2-fold greater in microsomes from embryonic liver than in mierosomes from adult liver. 3. 3. A maximum level of conversion of dolichyl pyrophosphate N-acetylglucosamine to dolichyl pyrophosphate N, N′-diacetylchitobiose was achieved at 5 mM concentration of unlabelled UDP- N-acetylglucosamine, while this conversion was negligible at lower UDP- N-acetylglucosamine concentrations (0.1 and 0.5 mM). 4. 4. The level of dolichyl phosphate, assessed by the level of dolichyl pyrophosphate N-acetylglucosamine synthesis was 2-fold higher in microsomes from embryonic liver than that in microsomes from adult liver. 5. 5. Tunicamycin (1 μg/ml) inhibited completely the formation of dolichyl pyrophosphate N-acetylglucosamine in embryonic liver microsomes, while the inhibitory effect of UMP (1 mM) was about 70%.