NUCLEAR MAGNETIC RESONANCE STUDIES OF INTERACTION OF TRYPTOPHAN WITH ALPHA-CHYMOTRYPSIN

The Michaelis complex formed by the interaction of tryptophan with α-chymotrypsin has been investigated by high-resolution nmr techniques. Appreciable line broadening is observed with both the D and L isomers of the amino acid. The D form appears to be more tightly bound to the enzyme than the L isomer. It is concluded that the binding is tight enough to imbue the bound tryptophan molecule with the same over-all rotational characteristics that characterize the motion of the enzyme in solution. Experiments with chemically modified enzymes suggest that tryptophan interacts with only one site on the enzyme and that this site is at or near the active site. © 1968, American Chemical Society. All rights reserved.