title: Specific inhibitory conformation of dipeptides for chymotrypsin.
abstract: Based on the analyzed conformation of a chymotrypsin inhibitor H-delta Phe-Phe-OMe, we have designed a series of diastereomeric phenylalanylphenylalanine methyl esters and derivatives as possible inhibitors. Among the peptides synthesized, H-D-Phe-L-Phe-OMe was found to be very resistant to chymotrypsin in spite of its L-Phe-OMe structure at the C-terminus. It inhibited the enzyme fairly strongly and competitively with Ki = 9.0 x 10(-5) M in the assay using Ac-Tyr-OEt as a substrate. The measurements of the NOEs in high-resolution 1H-NMR analyses indicated the presence of the hydrophobic core built by the intramolecular interaction between the D-Phe-phenyl and ester-methyl groups. It was suggested that this core interacts with the chymotrypsin S2 site (Trp215) and Phe2 with the S1 site. The backbone structure of this dipeptide was assumed to be in an inhibitory conformation that fits the active center of the enzyme.
authors.affiliation: Department of Chemistry, Faculty of Science, Kyushu University, Fukuoka, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Shimohigashi
authors.forename: T
authors.initials: T
authors.lastname: Ogawa
authors.forename: H
authors.initials: H
authors.lastname: Kodama
authors.forename: H
authors.initials: H
authors.lastname: Sakamoto
authors.forename: H
authors.initials: H
authors.lastname: Yoshitomi
authors.forename: M
authors.initials: M
authors.lastname: Waki
authors.forename: M
authors.initials: M
authors.lastname: Ohno
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002918:Chymotrypsin / Q000037:antagonists & inhibitors*; D004151:Dipeptides / Q000494:pharmacology*; D007700:Kinetics; D008969:Molecular Sequence Data; D011487:Protein Conformation; D013329:Structure-Activity Relationship
chemical_list: D004151:Dipeptides; C063009:phenylalanylphenylalanine methyl ester; D002918:Chymotrypsin