CaltechAUTHORS
  A Caltech Library Service

A nitrogen-15 nuclear magnetic resonance study of the acid-base and tautomeric equilibriums of 4-substituted imidazoles and its relevance to the catalytic mechanism of α-lytic protease

Roberts, John D. and Chun, Yu and Flanagan, Cynthia and Birdseye, Teresa R. (1982) A nitrogen-15 nuclear magnetic resonance study of the acid-base and tautomeric equilibriums of 4-substituted imidazoles and its relevance to the catalytic mechanism of α-lytic protease. Journal of the American Chemical Society, 104 (14). pp. 3945-3949. ISSN 0002-7863. http://resolver.caltech.edu/CaltechAUTHORS:20151005-120248113

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

Use this Persistent URL to link to this item: http://resolver.caltech.edu/CaltechAUTHORS:20151005-120248113

Abstract

The pH dependence of the ^(15)N NMR shifts of histamine, imidazole-4-propionic acid, imidazole-4-acetic acid, trans and cis-urocanic acid, and endo-cis-3-(4-imidazoyl)bicyclo[2.2.h1]e pt-5-ene-2-carboxylic acid has been determined at the natural-abundance level of ^(15)N. The chemical-shift changes permit calculation of pK_a values for the acidic species present as well as reasonably accurate positions of the Nl(H)⇌N3(H) tautomeric equilibria for those species having unprotonated imidazole rings. The ^(15)N shifts of cis-urocanic acid and endo-cis-3-(4-imidazoyl)bicyclo [2.2.1] hept-5-ene-2-carboxylic acid demonstrate that carboxylate-N3(H) hydrogen-bonding interactions can cause the N3(H) tautomers to be substantially more stable than the Nl(H) tautomers. The unusual positions of these tautomeric equilibria are quite similar to that found for the histidine of the catalytic triad of α-lytic protease.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx/doi.org/10.1021/ja00378a027DOIArticle
http://pubs.acs.org/doi/abs/10.1021/ja00378a027PublisherArticle
Additional Information:© 1982 American Chemical Society. Received September 23, 1981. Supported by the National Science Foundation and the National Institute of Health. We are very indebted to Dr. Keiko Kanamori for her suggestions and help with this investigation.
Funders:
Funding AgencyGrant Number
NSFUNSPECIFIED
NIHUNSPECIFIED
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Gates and Crellin Laboratories of Chemistry6537
Record Number:CaltechAUTHORS:20151005-120248113
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20151005-120248113
Official Citation:A nitrogen-15 nuclear magnetic resonance study of the acid-base and tautomeric equilibriums of 4-substituted imidazoles and its relevance to the catalytic mechanism of .alpha.-lytic protease John D. Roberts, Yu Chun, Cynthia Flanagan, and Teresa R. Birdseye Journal of the American Chemical Society 1982 104 (14), 3945-3949 DOI: 10.1021/ja00378a027
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:60763
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:05 Oct 2015 21:39
Last Modified:05 Oct 2015 21:39

Repository Staff Only: item control page