Temperature and photosynthesis. II. A mechanism for the effects of temperature on carbon dioxide fixation

Abstract

• 1.

  1. A simple model mechanism for photosynthetic CO₂ fixation which incorporates the autocatalytic features of the carbon cycle and a mechanism for bleeding off the intermediates has been postulated to account for the variation in and high values of the activation energy (Q₁₀) of CO₂ fixation.

• 2.

  2. The steady-state rate equation for the model is derived and its properties discussed. It is shown that the model can account for the effects of temperature on the rate of CO₂ fixation using reasonable values for the activation energies and heats of reaction of the kinetic constants.

• 3.

  3. The proposed type of mechanism is compatible with the lag period observed after rewarming whole cells, the lack of a marked effect of temperature on the lag period of isolated chloroplasts and the transient oscillations in the levels of intermediates observed after alteration of the CO₂ concentration.

• 4.

  4. The importance of the reaction in which intermediates are bled off as a control mechanism in systems involving stoichiometric amplification is considered.