... Marquardt method for parameter optimization. The half-height widths of the NMR signalswere used as a measure of the uncertainty of each NMRdata point and an experimental uncertainty of 2% wasassumed ... Comparison of these results with datafor the isolated cytochrome shows that binding of ligands causes only smallchanges in the reduction potentials of the haems and their pairwise inter-actions, ... Delgado R, Frausto da Silva JJR, Amorim MTS,Cabral MF, Chaves S & Costa J (1991) Dissociationconstants of Bronsted acids in D2O and H2O: studies on polyaza and polyoxa–polyaza macrocycles...