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NMR localization of protons in critical enzyme hydrogen bonds

Sharif, S. and Fogle, E. and Toney, M. D. and Denisov, G. S. and Shenderovich, I. G. and Buntkowsky, G. and Tolstoy, P. M. and Huot, M. C. and Limbach, H. H. (2007):
NMR localization of protons in critical enzyme hydrogen bonds.
In: Journal of the American Chemical Society, 129 (31), pp. 9558-+, [Online-Edition: http://apps.webofknowledge.com/full_record.do?product=WOS&se...],
[Article]

Abstract

Using N-15 NMR spectroscopy and hydrogen bond correlations, we have localized a mechanistically critical proton in aspartate aminotransferase in microcrystals and aqueous solution. It is in a H-bond between a carboxylate O of Asp222 and the pyridine nitrogen of pyridoxal-5'-phosphate. At neutral pH in water, aspartate and pyridine are unprotonated, but they share a proton in the enzyme. It is shown that such a binuclear base is typical for acid-base interactions in aprotic polar solvents. Active site H-bonds to Asp222 assist protonation of the pyridine nitrogen in the enzyme, which is considered a prerequisite for catalytic activity. We also show that acid-base behavior in enzymes should be modeled using aprotic polar solvents rather than aqueous solutions.

Item Type: Article
Erschienen: 2007
Creators: Sharif, S. and Fogle, E. and Toney, M. D. and Denisov, G. S. and Shenderovich, I. G. and Buntkowsky, G. and Tolstoy, P. M. and Huot, M. C. and Limbach, H. H.
Title: NMR localization of protons in critical enzyme hydrogen bonds
Language: English
Abstract:

Using N-15 NMR spectroscopy and hydrogen bond correlations, we have localized a mechanistically critical proton in aspartate aminotransferase in microcrystals and aqueous solution. It is in a H-bond between a carboxylate O of Asp222 and the pyridine nitrogen of pyridoxal-5'-phosphate. At neutral pH in water, aspartate and pyridine are unprotonated, but they share a proton in the enzyme. It is shown that such a binuclear base is typical for acid-base interactions in aprotic polar solvents. Active site H-bonds to Asp222 assist protonation of the pyridine nitrogen in the enzyme, which is considered a prerequisite for catalytic activity. We also show that acid-base behavior in enzymes should be modeled using aprotic polar solvents rather than aqueous solutions.

Journal or Publication Title: Journal of the American Chemical Society
Volume: 129
Number: 31
Uncontrolled Keywords: coli aspartate-aminotransferase escherichia-coli carboxylic-acids 10-18-ppm range h-1 resonances concanavalin-a model systems active-site solid-state pyridoxal
Divisions: 07 Department of Chemistry
07 Department of Chemistry > Physical Chemistry
Date Deposited: 27 Oct 2014 20:49
Official URL: http://apps.webofknowledge.com/full_record.do?product=WOS&se...
Additional Information:

196LW Times Cited:35 Cited References Count:31

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