The Sulfur Shift: An Activation Mechanism for Periplasmic Nitrate Reductase and Formate Dehydrogenase

• Type: Article in International Scientific Journal
• Date: 2013

Authors

Nuno M F S A Cerqueira (Author) FCUP; Pedro A Fernandes (Author) FCUP; Pablo J Gonzalez (Author) Other; Jose J G Moura (Author) Other; Maria J Ramos (Author) FCUP

Journal

Title: Inorganic Chemistry

Vol. 52

Pages: 10766-10772

ISSN: 0020-1669

Publisher: American Chemical Society

Indexing

ISI Web of Knowledge - 51 Citations

Scopus - 53 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-008-ESV

DOI: 10.1021/ic3028034

Abstract (EN): A structural rearrangement known as sulfur shift occurs in some Mo-containing enzymes of the DMSO reductase family. This mechanism is characterized by the displacement of a coordinating cysteine thiol (or SeCys in Fdh) from the first to the second shell of the Mo-coordination sphere metal. The hexa-coordinated Mo ion found in the as-isolated state cannot bind directly any exogenous ligand (substrate or inhibitors), while the penta-coordinated ion, attained upon sulfur shift, has a free binding site for direct coordination of the substrate. This rearrangement provides an efficient mechanism to keep a constant coordination number throughout an entire catalytic pathway. This mechanism is very similar to the carboxylate shift observed in Zn-dependent enzymes, and it has been recently detected by experimental means. In the present paper, we calculated the geometries and energies involved in the sulfur-shift mechanism using QM-methods (M06/(6-311++G(3df,2pd),SDD)//B3LYP/(6-31G(d),SDD)). The results indicated that the sulfur-shift mechanism provides an efficient way to enable the metal ion for substrate coordination.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7