Raman spectroscopic study of the changes in secondary structure of chymotrypsin: effect of pH and pressure on the salt bridge.
Conformational changes of alpha-chymotrypsin, induced by pH and pressure, have been studied with Raman spectroscopy. The secondary structure of alpha-chymotrypsin, chymotrypsinogen and DFP-chymotrypsin has been calculated by a singular value analysis of the Raman amide-I band. The changes in secondary structure, with pH and pressure titration of alpha-chymotrypsin, indicate a conformational transition. The salt bridge between Asp-194 and Ile-16 is disrupted, and the enzyme becomes inactive. No changes are observed for chymotrypsinogen. It is concluded that the proenzyme exhibits the same conformation at different pH values as alpha-chymotrypsin at alkaline pH. The results for DFP-chymotrypsin indicate that the active conformation is stabilized by the presence of the DFP inhibitor in the binding site.
Heremans
L
L
Department of Chemistry, Katholieke Universiteit Leuven, Belgium.
Heremans
K
K
D002918:Chymotrypsin; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008433:Mathematics; D008962:Models, Theoretical; D011312:Pressure; D011487:Protein Conformation; D013059:Spectrum Analysis, Raman / Q000379:methods
D002918:Chymotrypsin