title: alpha-D-mannopyranosylmethyl-p-nitrophenyltriazene inhibition of rat liver alpha-D-mannosidases.
abstract: The compound alpha-D-mannopyranosylmethyl-p-nitrophenyltriazene (alpha-ManMNT) has been tested for its effect on four alpha-D-mannosidase activities present in rat liver. When p-nitrophenyl alpha-D-mannopyranoside was used as a substrate, preincubation of enzyme with 1.0 mM alpha-ManMNT inhibited soluble alpha-D-mannosidase by 90%, lysosomal alpha-D-mannosidase by approx. 60%, and had virtually no effect on Golgi mannosidase II. Golgi mannosidase I removal of the four alpha-1,2-linked D-mannoses from the common Man9GlcNAc2 oligosaccharide structure formed during N-linked glycoprotein biosynthesis was also blocked by treatment of the Golgi fraction with this compound. Mannosyltriazene inhibition of the three susceptible hepatic alpha-D-mannosidases was largely irreversible. alpha-ManMNT should therefore be useful for studying oligosaccharide processing and possibly for determining the turnover time of the inhibited alpha-D-mannosidases.
mesh_terms: D000818:Animals; D003600:Cytosol / Q000201:enzymology; D006056:Golgi Apparatus / Q000201:enzymology; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008247:Lysosomes / Q000201:enzymology; D008361:Mannosidases / Q000037:antagonists & inhibitors*; D051381:Rats; D014226:Triazenes / Q000494:pharmacology*
chemical_list: D014226:Triazenes; C047982:mannopyranosylmethyl-4-nitrophenyltriazene; D008361:Mannosidases; C046090:mannosyl-oligosaccharide 1,2-alpha-mannosidase; C038829:mannosyl-oligosaccharide 1,3 - 1,6-alpha-mannosidase