Thermodynamics of protein-peptide interactions in the ribonuclease S system studied by titration calorimetry.
Two fragments of pancreatic ribonuclease A, a truncated version of S-peptide (residues 1-15) and S-protein (residues 21-124), combine to give a catalytically active complex designated ribonuclease S. Residue 13 in the peptide is methionine. According to the X-ray structure of the complex of S-protein and S-peptide (1-20), this residue is almost fully buried. We have substituted Met-13 with seven other hydrophobic residues ranging in size from glycine to phenylalanine and have determined the thermodynamic parameters associated with the binding of these analogues to S-protein by titration calorimetry at 25 degrees C. These data should provide useful quantitative information for evaluating the contribution of hydrophobic interactions in the stabilization of protein structures.
Connelly
P R
PR
Department of Chemistry, Yale University, New Haven, Connecticut 06511.
Varadarajan
R
R
Sturtevant
J M
JM
Richards
F M
FM
D000596:Amino Acids; D000818:Animals; D002151:Calorimetry / Q000379:methods; D002417:Cattle; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D008715:Methionine; D010446:Peptide Fragments; D010455:Peptides; D011487:Protein Conformation; D012260:Ribonucleases; D013816:Thermodynamics
D000596:Amino Acids; D010446:Peptide Fragments; D010455:Peptides; D008715:Methionine; D012260:Ribonucleases; C022542:ribonuclease S