This work presents an improved stopped-flow protocol for the simultaneous measurement of thermodynamic and kinetic protein stability data from a single experiment, along with a formalism for the global analysis of the data. The method was applied to the comparison of the stabilities of cytochrome c(6) from Anabaena sp. PCC 7119 and one of its mutants (D72K). Compared to the wild type the mutant was found to have a significantly reduced thermodynamic (DeltaDeltaG(U0) = 2.7 kJ mol(-1)) and kinetic stability, as well as a more pronounced shift in transition state structure upon destabilization. (C) 2003 Elsevier Inc. All rights reserved.