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Ultrasonic studies of proton‐transfer reactions at the catalytic site of α‐chymotrypsin
Author(s) -
Rogez Daniel,
Cerf Roger,
Andrianjara Razafindrabe,
Salehi Seyed-Taghi,
Fouladgar Hossein
Publication year - 1987
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(87)81183-3
Subject(s) - chemistry , catalysis , chymotrypsin , relaxation (psychology) , histidine , active site , proton , sulfite , analytical chemistry (journal) , crystallography , enzyme , inorganic chemistry , chromatography , organic chemistry , trypsin , psychology , social psychology , physics , quantum mechanics
Ultrasonic relaxation measurements for α‐chymotrypsin in phosphate, sulfite and arsenate buffers exhibit a high peak of absorption at neutral pH. The analysis is based on: (i) comparison of the relaxation measurements for the enzyme and for the zymogen and inhibited enzyme; (ii) X‐ray and neutron diffraction data, and high‐resolution NMR data. The ultrasonic relaxation is shown to result mainly from a proton‐transfer reaction that involves the histidine at the catalytic site (His‐57). The question is raised of whether the enhanced ultrasonic effect observed in the enzyme is indicative of a property that plays a part in the catalytic activity.