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Biological NMR Spectroscopy$
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John L. Markley and Stanley J. Opella

Print publication date: 1997

Print ISBN-13: 9780195094688

Published to Oxford Scholarship Online: November 2020

DOI: 10.1093/oso/9780195094688.001.0001

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PRINTED FROM OXFORD SCHOLARSHIP ONLINE (oxford.universitypressscholarship.com). (c) Copyright Oxford University Press, 2021. All Rights Reserved. An individual user may print out a PDF of a single chapter of a monograph in OSO for personal use. date: 23 October 2021

Chorismate Mutase, Essentially a Template Enzyme

Chorismate Mutase, Essentially a Template Enzyme

Chapter:
(p.235) 17 Chorismate Mutase, Essentially a Template Enzyme
Source:
Biological NMR Spectroscopy
Author(s):

W.N. Lipscomb

Y.M. Chook

Publisher:
Oxford University Press
DOI:10.1093/oso/9780195094688.003.0023

It was a particular pleasure for the senior author to open the scientific sessions which celebrated Oleg Jardetzky’s 65th birthday anniversary. Oleg was a student in my Physical Chemistry course at the University of Minnesota in 1950, and received an M.D, from the Medical School in 1954. At that time he came to my office to ask for a Ph.D. research problem in statistical mechanics of membrane processes, and I suggested that he study instead the NMR quadrupole line broadening of Na+ in solutions of small biologically interesting molecules as they interact with Na+. This research, with John Wertz, is surely an early study of biologically interesting problems using NMR, and I consider it a privilege to have helped to start Oleg on his outstanding career in this area of science. The enzyme chorismate mutase from Bacillus subtilis forms the topic of this chapter, and the method is single crystal X-ray diffraction. It is a very recent study and highlights some questions. Only 127 amino acids are present in the polypeptide chain, and the structure would be a candidate for NMR pulse methods, except that the molecule in the solution and in the crystal is trimeric. (We were told by the biochemists that it was dimeric!) Non-crystallographic symmetry (based on vector distances) was helpful in solving the structure, and I wonder if there is some partly equivalent use of molecular symmetry (based on scalar distances) that would simplify the analysis of the NMR spectrum of the trimer in solution. The second question is how nearly the same are the monomers in the crystallographic unit. In the crystal there are actually 12 monomers (i.e., 4 trimers)in the asymmetric unit of the crystal. When all 12 are superimposed the polypeptide chains are very similar indeed. No doubt the trimerization reduces the distortions of structure below those expected for isolated monomers. The third question relates to the chemical mechanism by which chorismate mutase isomerizes chorismate to prephrenate in a pericyclic reaction, the only pericyclic reaction that is known to be catalyzed by an enzyme.

Keywords:   chorismate mutase, x-ray crystallography

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