ON THE DETERMINATION OF THE S-STATE DISTRIBUTION IN THE KOK MODEL

We use the Markow chain theory to analyze the oscillation pattern of o xygen evolution during water oxidation in photosystem II under short s aturating light flashes. We propose a method based on the standard lea st square deviation (test chi(2)) to determine the number of S-states in the Kok model. As pointed out by Burda et al. (1995) this informati on is amongst others important for the interpretation of the role of c alcium for oxygen evolution. A specific mathematical representation fo r a situation when the S-4 state is longer living than generally assum ed is introduced which requires an explicit extension of the Kok model to five states The higher stability is modelled by introducing additi onal decay channels, e.g. a nonvanishing probability for the transitio n of S-3 to the S-0 state and a further transition probability for the transition from S-3 to S-4. Our analysis is extended to the case of d amped oscillations of oxygen evolution caused, for example, by the lac k of electron acceptor or the short life time of photosystem II partic les.