Theoretical study of the chemoselectivity of tungsten-dependent acetylene hydratase
2011 (English)In: ACS Catalysis, ISSN 2155-5435, Vol. 1, no 8, 937-944 p.Article in journal (Refereed) Published
The tungsten-dependent enzyme acetylene hydratase catalyzes the hydration of acetylene to acetaldehyde. Very recently, we proposed a reaction mechanism for this enzyme based on density functional calculations (Proc. Natl. Acad. Sci. U.S.A. 2010, 107, 22523). The mechanism involves direct coordination of the substrate to the tungsten ion, followed by a nucleophilic attack by a water molecule concerted with a proton transfer to a second-shell aspartate, which then reprotonates the substrate. Here, we use the same methodology to investigate the factors involved in the control of the chemoselectivity of this enzyme. The hydration reactions of three representative compounds (propyne, ethylene, and acetonitrile) are investigated using a large model of the active site. The energy of substrate binding to the metal ion and the barrier for the following nucleophilic attack are used to rationalize the experimental observations. It is shown that all three compounds have higher barriers for hydration compared with acetylene. In addition, propyne is shown to have a larger binding energy, explaining its behavior as a competitive inhibitor. Taken together, the results provide further corroboration of our suggested mechanism for acetylene hydratase
Place, publisher, year, edition, pages
2011. Vol. 1, no 8, 937-944 p.
acetylene hydratase, enzyme mechanism, chemoselectivity, transition state, density functional theory
IdentifiersURN: urn:nbn:se:su:diva-59991DOI: 10.1021/cs200242mISI: 000293488300014OAI: oai:DiVA.org:su-59991DiVA: diva2:432476
FunderSwedish Research Council