Conformation and Activity of Chymotrypsin: The pH-Dependent, Substrate-Induced Proton Uptake

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Science  19 Jul 1968:
Vol. 161, Issue 3838, pp. 274-276
DOI: 10.1126/science.161.3838.274


Hydrogen ion uptake by chymotrypsin during reversible binding of specific substrate is shown to be due to an ionizing group of the enzyme with a pK(apparent) ∼9 in the free enzyme. This pK(apparent) is shifted to higher value in the enzyme-substrate complexes. Previous results indicating an equilibrium, controlled by this ionizing group, between active and inactive conformational forms of chymotrypsin are confirmed.

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