Biosynthesis of dolichyl pyrophosphate n-acetylglucosaminyl intermediates in liver microsomes from hibernating ground squirrels ( citellus citellus l.)

Abstract

1. 1. Dolichyl pyrophosphate N- acetyl[ 14 C] glucosamine was synthesized after incubation of liver microsomes from hibernating ground squirrels with UDP- N-acetyl[ 14C]glucosamine. The radioactivity of glycolipid formed by liver microsomes from hibernating ground squirrels was about 2-fold greater than by liver microsomes from active animals. 2. 2. Addition of exogenous dolichyl phosphate to the incubation mixture increased the formation of dolichyl pyrophosphate N- acetyl[ 14 C] glucosamine by microsomes from both active and hibernating ground squirrels about 6 times. 3. 3. Liver microsomes from hibernating ground squirrels converted dolichyl pyrophosphate N- acetyl[ 14 C] glucosamine into dolichyl pyrophosphate N,N- diacetyl[ 14 C] chitobiose in the presence of unlabelled UDP- N-acetylglucosamine. This conversion was maximal at 1.0 M concentration of unlabelled UDP- N-acetylglucosamine. 4. 4. The level of dolichyl phosphate assessed by the level of dolichyl pyrophosphate N-acetylglucosamine formation was nearly 2 times greater in liver microsomes from hibernating ground squirrels than from active animals.