The Saccharomyces cerevisiae processing alpha 1,2-mannosidase is an inverting glycosidase.
The alpha 1,2-mannosidase from Saccharomyces cerevisiae, which removes one specific alpha 1,2-linked mannose residue from Man9GlcNAc2, is a member of the Class 1 alpha 1,2-mannosidase family conserved from yeast to mammals. Although Class 1 alpha 1,2-mannosidases are essential for the maturation of N-linked oligosaccharides in mammalian cells, nothing is known about their mechanism of action. The availability of sufficient quantities of recombinant yeast alpha 1,2-mannosidase and its homology with the mammalian enzymes make it a good model to study the catalytic mechanism of this family of alpha 1,2-mannosidases. The stereochemical course of hydrolysis of Man9GlcNAc by the yeast enzyme was followed by proton nuclear magnetic resonance spectroscopy. It was observed that beta-D-mannose is related from the oligosaccharide substrate, thereby demonstrating that the enzyme is of the inverting type.
Lipari
F
F
McGill Cancer Centre, McGill University, Montréal, Québec, Canada.
Gour-Salin
B J
BJ
Herscovics
A
A
D002240:Carbohydrate Sequence; D006026:Glycoside Hydrolases / Q000378:metabolism*; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D008351:Mannans / Q000737:chemistry / Q000378:metabolism; D008361:Mannosidases / Q000378:metabolism*; D008969:Molecular Sequence Data; D011499:Protein Processing, Post-Translational; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013237:Stereoisomerism
D008351:Mannans; C057328:mannosyl(9)-N-acetylglucosamine; D006026:Glycoside Hydrolases; D008361:Mannosidases; C046090:mannosyl-oligosaccharide 1,2-alpha-mannosidase