New reagents for spectral titration of active site of chymotrypsin.
JOURNAL OF BIOCHEMICAL AND BIOPHYSICAL METHODS 1993;
27:261-5. [PMID:
8258641 DOI:
10.1016/0165-022x(93)90007-b]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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.
Collapse