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

• Type: Article in International Scientific Journal
• Date: 2021

Authors

Teixeira, CSS (Author) Other; Sergio Filipe Sousa (Author) FCUP; Cerqueira, NMFSA (Author) Other

Journal

Title: ChemPhysChem

Vol. 22

Pages: 796-804

ISSN: 1439-4235

Publisher: Wiley-Blackwell

Indexing

ISI Web of Knowledge - 3 Citations

Scopus - 3 Citations

Other information

Authenticus ID: 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).

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 10