Action and Metabolic Control

Sucrose synthase (SuSy) provides another potential pathway for eontrolling cellulose production. SuSy cleaves sucrose in the presence of uridine diphosphate (UDP) into UDP-glucose and fructose, thereby conserving the energy of the glycosidic bond  

This parameter falls within the range of values from 1.4 to 8 determined experimentally based on substrate concentrations at equilibrium (Cardini et al. 1955 Neufeld and Hassid 1963 Avigad 1964 Kruger 1997). Since this reaction is thermodynamically close to equilibrium, the net flux (v = - v ) will repre- 

The net flux in vivo through SuSy can be altered by a relatively small shift in the mass action ratio away from its equilibrium position (Keq). To obtain net flux in favor of UDP-glucose formation, the reaction must be displaced from equilibrium 

an increase in the divergence of mass action ratio in vivo will increase the change in free energy through the reaction. This disequilibrium ratio can also be linked to flux by the ratio of the forward and reverse reaction velocities according to the equation derived by Hess and Brand (1965) from a rate equation based on Michaelis-Menten kinetics  

The cytoplasmic concentrations chosen for each metabolite are not only associated with the range found in the literature but also close to the ranges of apparent 

---