A Caltech Library Service

Imidazole-Ligated Compound I Intermediates: The Effects of Hydrogen Bonding

Green, Michael T. (2000) Imidazole-Ligated Compound I Intermediates: The Effects of Hydrogen Bonding. Journal of the American Chemical Society, 122 (39). pp. 9495-9499. ISSN 0002-7863. doi:10.1021/ja994377k.

Full text is not posted in this repository. Consult Related URLs below.

Use this Persistent URL to link to this item:


An unresolved issue of peroxidase activity is the role played by the hydrogen bond between the proximal histidine ligand and a highly conserved aspartate group. It has been postulated that this hydrogen bond imparts imidazolate character to the axial ligand, increasing its donating ability and stabilizing the high valent compound I intermediate. A general feature of biological compound I intermediates is that they display weaker spin couplings than model systems. To understand how the Asp-His hydrogen bond affects the electronic structure of the compound I intermediate and to establish a connection between it and the decreased coupling strengths observed in peroxidases, we have perfomed density functional calculations on imidazole- and imidazolate-ligated perferryl porphyrin species. It was found that the imidazolate compound I intermediate possesses an imidazolate-based radical, while the imidazole compound I intermediate possesses a porphyrin-based radical. Delocalizaton of the radical onto the axial ligand was found to reduce the strength of the spin coupling.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle
Additional Information:© 2000 American Chemical Society. Received December 15, 1999. Publication Date (Web): September 16, 2000. The author thanks Harry Gray, the Burroughs Wellcome Fund, and the National Institutes of Health for supporting this research.
Funding AgencyGrant Number
Burroughs Wellcome FundUNSPECIFIED
Issue or Number:39
Record Number:CaltechAUTHORS:20161018-135415365
Persistent URL:
Official Citation:Imidazole-Ligated Compound I Intermediates:  The Effects of Hydrogen Bonding Michael T. Green Journal of the American Chemical Society 2000 122 (39), 9495-9499 DOI: 10.1021/ja994377k
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:71231
Deposited By: George Porter
Deposited On:18 Oct 2016 21:15
Last Modified:11 Nov 2021 04:41

Repository Staff Only: item control page