New reagents for spectral titration of active site of chymotrypsin.
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.
Park
H S
HS
Department of Chemistry, Seoul National University, South Korea.
Lee
S
S
Suh
J
J
D002918:Chymotrypsin / Q000032:analysis*; D007202:Indicators and Reagents / Q000737:chemistry; D010080:Oxazoles / Q000737:chemistry*; D013053:Spectrophotometry; D013237:Stereoisomerism
D007202:Indicators and Reagents; D010080:Oxazoles; C084827:2-phenyl-(4-cinnamylidene)oxazolin-5-one; D002918:Chymotrypsin