title: Modeling the effect of temperature and pH on activity of enzymes: the case of phytases.
abstract: In this study, the behavior of enzyme activity as a function of pH and temperature is modeled on the basis of fundamental considerations. A formulation is developed that includes the activation of enzymes with increasing temperatures and the deactivation of enzymes at higher temperature, together with the effect of protonation and hydroxylation on activity at various constant pH levels. The model is calibrated and validated against an extensive set of experimental data on phytases from seven different origins. The percentage variance accounted for (R(2)(adj)), obtained by statistical nonlinear regression analysis on all data sets, was shown to range from 97.6% to 99.5%. The equilibrium constant of protonation and hydroxylation proved to be independent of temperature.
authors.affiliation: ATO-DLO, P.O. Box 17, 6700 AA Wageningen, The Netherlands. l.m.m.tijskens@ato.wag-ur.nl
authors.forename: L M
authors.initials: LM
authors.lastname: Tijskens
authors.forename: R
authors.initials: R
authors.lastname: Greiner
authors.forename: E S
authors.initials: ES
authors.lastname: Biekman
authors.forename: U
authors.initials: U
authors.lastname: Konietzny
mesh_terms: D010832:6-Phytase / Q000096:biosynthesis / Q000378:metabolism*; D001419:Bacteria / Q000201:enzymology; D004789:Enzyme Activation; D006863:Hydrogen-Ion Concentration; D006900:Hydroxylation; D008954:Models, Biological; D010944:Plants / Q000201:enzymology; D011522:Protons; D012044:Regression Analysis; D015203:Reproducibility of Results; D013696:Temperature
chemical_list: D011522:Protons; D010832:6-Phytase