The role of the protein core in the inhibitory power of the classic serine protease inhibitor, chymotrypsin inhibitor 2.
A synthetic cyclic peptide, reported to be a tight-binding inhibitor of serine proteases, is instead found to be a good substrate, as is the linear peptide of the same sequence. Both of the peptides, designed to mimic the binding loop of chymotrypsin inhibitor 2 (CI2), were cleaved by subtilisin primarily at the CI2 reactive-site Met-59-Glu-60 bond, revealing that the sequence, in the absence of the structural context of the inhibitor, provides sufficient specificity for hydrolysis of this bond. Insights from the crystal structure of the CI2/subtilisin complex, together with biochemical analysis of a CI2 Gly-83 deletion mutant, have allowed us to identify key features that make CI2 an effective inhibitor, while the cyclic and linear peptides are substrates.
Radisky
Evette S
ES
Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA.
King
David S
DS
Kwan
Gene
G
Koshland
Daniel E
DE
D001412:Bacillus subtilis / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000378:metabolism; D017353:Gene Deletion; D006860:Hydrogen Bonding; D006868:Hydrolysis; D007700:Kinetics; D008958:Models, Molecular; D009154:Mutation; D010455:Peptides / Q000737:chemistry*; D010940:Plant Proteins; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013997:Time Factors
D010455:Peptides; D010940:Plant Proteins; D011506:Proteins; D011994:Recombinant Proteins; D015842:Serine Proteinase Inhibitors; C093336:chymotrypsin inhibitor 2