Regulatory Behavior of Monomeric Enzymes

摘要: A new concept, that of a mnemonical transition, is proposed to explain the departure from Michaelian behavior monomeric enzymes following ordered reaction mechanisms. The concept integrates three simple ideas: free enzyme occurs under two conformational states in equilibrium; collision any these forms with first substrate induces same third configuration required for proper binding; only one last product stabilizes form without change. This whole set definitions equivalent assuming which released after catalysis, conformation different initial one. can be said “recall” while stabilized by before relapsing conformation. non-hyperbolic thus consequence cooperation conformations overall process. The reciprocal steady-state rate equations have been established and thoroughly discussed both one-substrate, one-product two-substrate, two-product enzymes. does not appear as slow but defined simpler way relative values activation energies changes binding on forms. A an mechanism exhibiting transition has very distinctive kinetic behavior. curvature primary plots observed regard only, independant concentration second well product. inhibited excess are either concave up or down. slopes intercepts straight lines obtained double should give, when replotted against concentration, line curve, respectively. process positive negative. Since cannot exhibit extreme, extent measured numerical value derivative equation. between highly controlled If was already negative, strengthens cooperation. If, other hand, positive, decreases even reverses cooperation. A general property one-sited isotherms.