Primary C-13 and beta-secondary H-2 KIEs for trans-sialidase. A snapshot of nucleophilic participation during catalysis

Primary C-13 and beta-secondary H-2 KIEs for trans-sialidase. A snapshot of nucleophilic participation during catalysis

Autor Yang, J. S. Google Scholar
Schenkman, S. Google Scholar
Horenstein, B. A. Google Scholar
Instituição Univ Florida
Universidade Federal de São Paulo (UNIFESP)
Resumo Trypanosoma cruzi trans-sialidase catalyzes a novel reaction that involves the transfer of sialic acid between host and parasite glycoconjugates. in this paper, we report kinetic isotope effect studies on recombinant trans-sialidase. beta-Dideuterium and primary C-13 isotope effects were measured for a good substrate, sialyl-lactose, and a slow substrate, sialyl-galactose, in both acid-catalyzed solvolysis and enzymatic transfer reactions. the beta-dideuterium isotope effect for sialyl-lactose in the acid hydrolysis reaction was 1.113 +/- 0.012, the primary C-13 isotope effects for hydrolysis of sialyl-lactose and sialyl-galactose were 1.016 +/- 0.011 and 1.015 +/- 0.008, respectively. III the enzymatic transfer reactions, the B-dideuterium and primary C-13 effects for sialyl-galactose were 1.060 +/- 0.008 and 1.032 +/- 0.008, respectively. the isotope effects for hydrolysis describe a dissociative S(N)1-like mechanism, and these data are contrasted by the data for the enzyme-catalyzed reaction. the enzymatic deuterium isotope effects are lower by a factor of 2, but the primary carbon isotope effects are higher by a factor of 2. This pattern describes a mechanism involving nucleophilic participation in the rate-determining transition state.
Idioma Inglês
Data de publicação 2000-05-16
Publicado em Biochemistry. Washington: Amer Chemical Soc, v. 39, n. 19, p. 5902-5910, 2000.
ISSN 0006-2960 (Sherpa/Romeo, fator de impacto)
Publicador Amer Chemical Soc
Extensão 5902-5910
Fonte http://dx.doi.org/10.1021/bi000061+
Direito de acesso Acesso restrito
Tipo Artigo
Web of Science WOS:000087002800031
Endereço permanente http://repositorio.unifesp.br/handle/11600/26312

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