Dependence of Oxygen Affinity for Mehler Reaction on Photochemical Activity of Chloroplast Thylakoids

摘要

The affinity of oxygen (apparentKm) for the photoreduction of molecular oxygen by class II spinach chloroplasts increased with an increase in light intensity. Using a reaction scheme in which the photoreduction of oxygen occurs via the spontaneous oxidation of an electron acceptor of photosystem I, P430, we inferred that the“Km”value is a ratio of the first-order rate constants of photoreduction of P430 plus the internal back decay of the reduced P430 to the second-order rate constant for the oxidation of reduced P430 with oxy