Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 26 May 1989:
Vol. 244. no. 4907, pp. 961 - 964
DOI: 10.1126/science.2499045
Prev | Table of Contents | Next

Articles

Science, Vol 244, Issue 4907, 961-964
Copyright © 1989 by American Association for the Advancement of Science

articles

Crystal versus solution structures of enzymes: NMR spectroscopy of a crystalline serine protease

SO Smith, S Farr-Jones, RG Griffin, and WW Bachovchin

Francis Bitter National Magnet Laboratory, Massachusetts Institute of Technology, Cambridge 02139.

The hydrogen-bonding status of His57 in the catalytic triad (Asp-His-Ser) of serine protease has important mechanistic implications for this class of enzymes. Recent nitrogen-15 nuclear magnetic resonance (NMR) studies of alpha-lytic protease find His57 and Ser195 to be strongly hydrogen-bonded, a result that conflicts with the corresponding crystallographic studies, thereby suggesting that the crystal and solution structures may differ. This discrepancy is addressed and resolved in a nitrogen-15 NMR study of the enzyme in the crystalline state. The results show that the His-Ser and Asp-His interactions are identical in crystals and solutions, but that in crystals His57 titrates with a pKa of 7.9, nearly one pKa unit higher than in solution. This elevated pKa accounts for the absence of the His-Ser hydrogen bond in previous x-ray studies.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Histidines, heart of the hydrogen ion channel from influenza A virus: Toward an understanding of conductance and proton selectivity.
J. Hu, R. Fu, K. Nishimura, L. Zhang, H.-X. Zhou, D. D. Busath, V. Vijayvergiya, and T. A. Cross (2006)
PNAS 103, 6865-6870
   Abstract »    Full Text »    PDF »


To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)