Thermodynamic Efficiency in Pumped Biochemical Reactions

We investigate the problem of establishing a concentration gradient, say across a membrane. This establishment requires energy, for example from ATP. In turn the gradient may be used to do work in the surroundings of the system. The subject is closely related to the issue of the efficiency of biological pumps, such as pumps for sodium ions, potassium ions, and protons. 

The energy of the light absorbed by the chromatophore in A can establish and maintain a chemical potential difference in FDP and F6P, which may be used to do work. For discussions of the use of light to drive systems away from equilibrium see [2-6]. 

The deterministic kinetic equations for this system are highly nonlinear because of both the chromatograph reaction and the PFK reaction. (These 

There are several different dynamic domains possible at stationary state stable nodes, sn stable foci, sf and unstable foci, uf, that is stable oscillations. 

We can study this system with a constant input of light intensity or an oscillatory input of light intensity with a given frequency and amplitude. Three cases, marked I, II, and III, are shown in Fig. 17.2 for which calculations were made of the efficiency of energy transduction from light to work two of these are within a region of a stable focus, and one within a region of a limit cycle. 

---