Mapping the carbon reduction cycle: a personal retrospective

The photosynthetic carbon reduction cycle was elucidated through the use of ¹⁴CO₂ during photosynthesis to label metabolic intermediates. Mapping and proof of the cycle required identification of labeled metabolites, observation of changes in levels of labeled metabolites during transitions from light to dark and from high to low CO₂ levels, determination of intramolecular distribution of ¹⁴C within the metabolites after a few seconds of photosynthesis with ¹⁴CO₂, and estimation of metabolite concentrations, used to calculate true free energy changes at each step in the cycle. This revised version was published online in August 2006 with corrections to the Cover Date.