title: New reagents for spectral titration of active site of chymotrypsin.
abstract: The reaction of alpha-chymotrypsin (ChT) with 2-phenyl-(E)-[4-(E)-cinnamylidene]oxazolin-5-one (E-PCO) or 2-phenyl-(Z)-[4-(E)-cinnamylidene]oxazolin-5-one (Z-PCO) at pH 4.5 and 25 degrees C led to the quantitative accumulation of the corresponding acyl-ChT intermediate. Very large changes in molar extinction coefficient were observed in the visible region during the conversion of the oxazolinones to the acyl-ChT intermediates. This afforded a reliable method for the spectral titration of ChT in the visible region. Both E-PCO and Z-PCO were stable under these conditions and did not cause any complication in the titration of the active site.
authors.affiliation: Department of Chemistry, Seoul National University, South Korea.
authors.forename: H S
authors.initials: HS
authors.lastname: Park
authors.forename: S
authors.initials: S
authors.lastname: Lee
authors.forename: J
authors.initials: J
authors.lastname: Suh
mesh_terms: D002918:Chymotrypsin / Q000032:analysis*; D007202:Indicators and Reagents / Q000737:chemistry; D010080:Oxazoles / Q000737:chemistry*; D013053:Spectrophotometry; D013237:Stereoisomerism
chemical_list: D007202:Indicators and Reagents; D010080:Oxazoles; C084827:2-phenyl-(4-cinnamylidene)oxazolin-5-one; D002918:Chymotrypsin