Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published June 1972 | public
Journal Article

Magnetic resonance studies of protein-small molecule interactions. Binding of N-trifluoroacetyl-D-(and L-)-p-fluorophenylalanine to α-chymotrypsin

Abstract

Magnetic resonance studies of the interaction of N-trifluoroacetyl-n-(and L-)p-fluorophenylalanine with α-chymotrypsin have been used to investigate the molecular details of the enzyme-inhibitor interaction including the effect of pH (from 5.0 to 8.0). The principles of the technique are described. We conclude that the trifluoroacetyl group of then isomer interacts with the catalytic locus (His-57, Ser-195) while that of the L isomer is directed toward Ser-214. The aromatic ring of both then and L isomer resides in the hydrophobic pocket. The binding constant for the n isomer increases with neutralization of a group which has pK. of 6.6 in the free-enzyme (presumably His-57). The dimerization of chymotrypsin strongly affects the quantitative results and has been explicitly included in the analysis.

Additional Information

© 1972 American Chemical Society. Received October 6, 1971. This work was supported by a grant from the U. S. Public Health Service (GM-16424). One of us (K. L. G.) is also grateful for the support of an NSF Fellowship. The titrant was synthesized by R. B. Moon, who also carried out some early magnetic resonance studies on analogous systems. M. Hunkapiller and M. McMillan also contributed valuable synthetic assistance.

Additional details

Created:
August 19, 2023
Modified:
October 23, 2023