Related Experiment Video
Updated: Dec 31, 2025

Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes
Published on: January 16, 2016
Mannosidase mechanism: at the intersection of conformation and catalysis
Carme Rovira1, Alexandra Males2, Gideon J Davies2
1Departament de Química Inorgànica i Orgànica (Secció de Química Orgànica) & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Pg. Lluís Companys 23, 08010 Barcelona, Spain.
Abstract:
Mannosidases are a diverse group of enzymes that are important in the biological processing of mannose-containing polysaccharides and complex glycoconjugates. They are found in 12 of the >160 sequence-based glycosidase families. We discuss evidence that nature has evolved a small set of common mechanisms that unite almost all of these mannosidase families. Broadly, mannosidases (and the closely related rhamnosidases) perform catalysis through just two conformations of the oxocarbenium ion-like transition state: a B2,5 (or enantiomeric 2,5B) boat and a 3H4 half-chair. This extends to a new family (GT108) of GDPMan-dependent β-1,2-mannosyltransferases/phosphorylases that perform mannosyl transfer through a boat conformation as well as some mannosidases that are metalloenzymes and require divalent cations for catalysis. Yet, among this commonality lies diversity. New evidence shows that one unique family (GH99) of mannosidases use an unusual mechanism involving anchimeric assistance via a 1,2-anhydro sugar (epoxide) intermediate.
Related Concept Videos
Introduction to Mechanisms of Enzyme Catalysis
ATP Synthase: Mechanism
Enzymes
Enzyme deficiencies can often translate into life-threatening diseases. For example, a genetic abnormality resulting in the deficiency of the enzyme G6PD...
Allosteric Proteins-ATCase
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis...
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution

