Wavelength-dependent kinetics center

Kirmaier, C., Holten, D., and Parson, W. W., 1985a, Temperature and detection-wavelength dependence of the picosecond electron transfer kinetics measured in Rhodopseudomonas sphaeroides reaction centers Resolution of new spectral and kinetic components in the primary charge-separation process. Biochim. Biophys. Acta, 810 33n48. 

There are at least three mechanisms for the reversal of NO inhibition of an enzyme. The most obvious is that the NO can be released as the concentration of NO in solution falls or the temperature rises. This depends on the (kinetic) off constant for NO in the system in question as well as the (equilibrium) dissociation constant for most enzymes that form nitrosyl complexes, this has not been measured. Nitric oxide bound to a metal center could also undergo oxidation or reduction followed by the release of product. Finally, NO could be photodissociated from a metal center by light of the correct wavelength. 

The UV photon may be assumed to have an energy less than the band gap of the phosphor host so the absorption by A, S, and P takes place at the centers. Many activators, particularly Mn2+, have a low absorption cross-section so that direct pumping of the activator is inefficient. Sensitizers, such as Pb2+, are selected to have large absorption cross-sections at UV wavelengths. They then transfer the excitation to the activator which re-emits it as luminescent radiation. Most co-activators have a luminescent emission of their own so that the efficiency of the system depends on the kinetics of energy transfer compared with direct emission of the co-activator. In many mineral systems, one observes both and thus the activator radiation Ra and the sensitizer radiation Rg are... 

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