An Unsual Cys-Glu-Lys Catalytic Triad is Responsible for the Catalytic Mechanism of the Nitrilase Superfamily: A QM/MM Study on Nit2

• Tipo: Artigo em Revista Científica Internacional
• Data: 2021

Autores

Teixeira, CSS (Autor) Outra; Sergio Filipe Sousa (Autor) FCUP; Cerqueira, NMFSA (Autor) Outra

Revista

Título: ChemPhysChem

Vol. 22

Páginas: 796-804

ISSN: 1439-4235

Editora: Wiley-Blackwell

Indexação

ISI Web of Knowledge - 3 Citações

Scopus - 3 Citações

Outras Informações

ID Authenticus: P-00T-P79

DOI: 10.1002/cphc.202000751

Abstract (EN): Nitrilase 2 (Nit2) is a representative member of the nitrilase superfamily that catalyzes the hydrolysis of alpha-ketosuccinamate into oxaloacetate. It has been associated with the metabolism of rapidly dividing cells like cancer cells. The catalytic mechanism of Nit2 employs a catalytic triad formed by Cys191, Glu81 and Lys150. The Cys191 and Glu81 play an active role during the catalytic process while the Lys150 is shown to play only a secondary role. The results demonstrate that the catalytic mechanism of Nit2 involves four steps. The nucleophilic attack of Cys191 to the alpha-ketosuccinamate, the formation of two tetrahedral enzyme adducts and the hydrolysis of a thioacyl-enzyme intermediate, from which results the formation of oxaloacetate and enzymatic turnover. The rate limiting step of the catalytic process is the formation of the first tetrahedral intermediate with a calculated activation free energy of 18.4 kcal/mol, which agrees very well with the experimental k(cat) (17.67 kcal/mol).

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 10