THE RELATION OF PROTEIN STRUCTURE TO THE CATALYTIC PROPERTIES OF ENZYMES.
Final rept. 1 May 58-30 Sep 67,
CORNELL UNIV ITHACA N Y
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Investigations of structural and functional relationships in reactions catalyzed by enzymes, mainly the hydrolytic enzyme chymotrypsin, were carried out through elucidation of individual reaction steps. This was done by characterizing and measuring physical and chemical changes in the enzyme which accompany the reactions under various conditions of pH and temperature and with various substrates and by making kinetic studies of these physical changes. This approach yields information not obtainable with the usual steady state approach, which may yield only combinations of rate and equilibrium constants. Results obtained in these experiments with enzyme in solution correlate well with independent x-ray diffraction studies of crystalline chymotrypsin by Blow and coworkers, and indications are that the approach and methods developed and used in this project, in conjunction with future x-ray diffraction experiments on crystalline materials, can provide detailed information needed for an understanding of the specificity and efficiency of reactions catalyzed by chymotrypsin and other hydrolytic enzymes. The work done so far has led to the development of an hypothesis concerning the conversion of chymotrypsinogen to chymotrypsin, a resulting pH-dependent equilibrium between enzyme conformations and the binding of substrate to enzyme. Other results obtained include the measurement, by flow and relaxation techniques, of six rate constants five not previously determined pertaining to intermediates in chymotrypsin-catalyzed reactions. Author