Mannosyltransferase Activity in Calf Pancreas Microsomes

摘要: Abstract Calf pancreas microsomes incorporated radioactive mannose from GDP-d-[14C]mannose into products precipitated by 6 % trichloroacetic acid-0.5 phosphotungstic acid. This incorporation was maximally stimulated 10 mm Mn2+ ions and showed a broad pH optimum of 6.0 to 6.7 in Tris-maleate buffer. Between 70 90 the radioactivity found soluble chloroform-methanol (2:1, v/v). The rates labeling extract residual precipitate were constant for 30 min, respectively. rough incubated with contained single 14C-labeled product, which stable under weak alkaline conditions yielded [14C]mannose upon mild acid hydrolysis some [14C]mannosyl phosphate hot treatment. It co-chromatographed on silica gel thin layer plates authentic dolichyl α-d-mannopyranosyl seven solvent systems, could be clearly separated P1-dolichyl P2-α-d-mannopyranosyl pyrophosphate ficaprenyl phosphate, mannolipid having shorter polyprenol moiety. [14C]-mannolipid did not undergo hydrogenolysis during catalytic hydrogenation released allylic polyprenyl mannosyl phosphates. Thus formed endogenous lipid is very similar phosphate. Dolichyl solanesyl (and limited extent retinyl phosphate) acted as exogenous acceptors d-mannose presence 0.1 Triton X-100 yield corresponding labeled that lipid, and, like pancreatic mannolipid, it hydrogenolysis. different mannolipids phosphates distinguished one another chromatograms, according length their moieties.