A unified theory for the basis of the limitations of the primary reaction of photosynthetic CO(2) fixation: was Dr. Pangloss right?

A s CO2 concentrations continue to rise and discussions on global warming assume ever more warning tones, understanding of the CO2 cycle between the atmosphere and biosphere becomes ever more important. Most CO2 enters the biosphere through the actions of Rubisco, an enzyme found in all plants and many microorganisms. For many of these organisms, this entry into the biosphere via the C3 carbon reduction cycle is fraught with impediments associated with particular attributes of this enzyme. At one time, Rubisco, because of its poor performance, was not considered up to the task of being the primary agent for atmospheric CO2 fixation. Although its role in this capacity was for some years in serious doubt, we know now that this most abundant enzyme is in fact the primary agent. However, as its numerous idiosyncratic features have revealed themselves, it has become clearer just how tenuous this primary reaction really is.