title: Catalysis by nucleoside hydrolases.
abstract: Nucleoside hydrolases cleave the N-glycosidic bond of ribonucleosides. Because of their vital role in the protozoan purine salvage pathway, nucleoside hydrolases from parasitic protozoa in particular have been studied extensively by X-ray crystallography, kinetic methods and site-directed mutagenesis. An elaborate network of conserved interactions between the metalloenzyme and the ribose enables steric and electrostatic stabilisation of the oxocarbenium-ion-like transition state. Activation of the leaving group by protonation before the formation of the transition state is a recurring catalytic strategy of enzymes that cleave N-glycosidic bonds. However, the mechanisms underlying leaving group activation are still the subject of debate for the nucleoside hydrolases.
authors.affiliation: Department of Ultrastructure, Vlaams Interuniversitair Instituut voor Biotechnologie, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel, Belgium. wversees@vub.ac.be
authors.forename: Wim
authors.initials: W
authors.lastname: Versées
authors.forename: Jan
authors.initials: J
authors.lastname: Steyaert
mesh_terms: D001665:Binding Sites; D002384:Catalysis; D004789:Enzyme Activation; D009699:N-Glycosyl Hydrolases / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D012266:Ribose / Q000737:chemistry*; D040681:Structural Homology, Protein; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D012266:Ribose; D009699:N-Glycosyl Hydrolases