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QCMP075. pHENZY: Program to Conform the pH Dependence
of the Michaelis Parameters of Nonallosteric
Enzymes to Four Kinetic Schemes
by Fernando J. Vega-Catalan, Computer Science Department, University of Ibadan, Ibadan, Nigeria The study of the pH dependence of the Km and Vmax parameters of the Michaelis-Menten equation provides valuable information about enzymes. It can help in identifying the kinetic scheme followed by the enzyme- catalyzed reaction and in establishing the ionization constants of the amino-acid chain groups which determine the enzyme's activity. This program fits the Km and Vmax versus pH experimental profiles to four kinetic mechanisms described by Tipton and Dixon. The fit is obtained via a nonlinear optimization search with starting values generated by the program, which relieves the user from having to enter a good initial estimate for the nonlinear fit. The program is menu driven and provides best-fit plots and residual plots along with the best-fit parameters and their uncertainties. Borland TURBO PASCAL (v. 4.0 or later) Lines of Code: 1675 |