Kinetic Model for Bifunctional Multisubstrate Enzymes. Steady-state Approximation

P. V. Vrzheshch

Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119899 Russia; fax: (095) 938-2323; E-mail: vrzh@genebee.msu.su

Received June 29, 1998

---

The steady-state approximation of the generalized model of a bifunctional multisubstrate enzyme is considered. Cases when the reactions catalyzed by the bifunctional enzyme are independent of one another and when one reaction influences the other are considered. Shunting of the kinetic mechanisms and activation of one reaction by the second reaction catalyzed by the bifunctional enzyme are analyzed. The kinetic equations are derived and qualitatively analyzed. It is shown in all cases discussed that the functional relationships between the kinetic parameters observed and the concentrations of the substrates participating in the reactions can be unambiguously defined on the basis of the concept of relationship of the intermediate enzyme forms in the enzymatic process.

---

KEY WORDS: bifunctional enzymes, multisubstrate reactions, generalized kinetic model, criteria of kinetic behavior

---