XVI International Botanical Congess

Oxidation-reduction midpoint potentials at pH 7.0 have been measured for thioredoxins f (-290 mV) and m (-300 mV), for ferredoxin:thioredoxin reductase (-320 mV), for spinach phosphoribulokinase (-290 mV), for fructose-1,6-bisphosphatase from pea (-315 mV) and spinach (-330 mV) and for sorghum NADP-malate dehydrogenase (-330 mV). Em vs. pH dependences have established limiting values for the pKa of the regulatory thiols. Titrations of site-specific mutants have established Em values for individual regulatory disulfides.