Modeling the Kinetics of Activation and Reaction of Rubisco from Gas Exchange

Abstract

Oxygenic life begins with photosynthesis. This process controls natural CO2 sequestration and is responsible for terrestrial and marine life on the planet. An increase in the global CO2/O2 concentration ratio creates positive feedback cycles, which in the atmosphere, lead to increases in temperature and water holding capacity. In the oceans, the holding capacities of CO2 and other gases are decreased, leading to their release into the atmosphere and accelerated climate change. Rubisco kinetic models are used as core modules for simulations of agricultural and natural productivity, environmental and ecological management, and climate change. Thus, a scientific theory that can be used reliably as the core module of such interactive processes is essential for maintaining the vitality of the planet. This chapter provides a comparison of the kinetic theories for Rubisco activation and reaction and their mathematical models. The two dominant schools of thought in the theory of Rubisco reaction are (1) the single-process or co-limitation theory and (2) the two-process theory. In the single-process theory, Rubisco is the gatekeeper and thus the paramount controller of CO2 fixation under any condition. The most widely used two-process theory assumes that carboxylation is limited by one of the two independent processes: (a) fully-activated RuBP-saturated capacity of Rubisco at low CO2, and (b) RuBP regeneration capacity at high CO2. The single-process model is consistent with a biochemically correct understanding of Rubisco reaction.