title: Transition state of an unfolding step in human cyanomet myoglobin.
abstract: We studied an unfolding step of cyanomet myoglobin (Mb) unfolding, for demonstrating dynamical structural changes in the transition state of the process. Three leucine-->alanine mutant Mbs (L29A, L72A and L104A) were prepared for this study. The urea-induced largely monophasic process was monitored by absorption spectroscopy. Linear relations between [urea] and the activation energy (delta G not equal to) of the relaxation for all the Mbs showed that the slope m not equal to urea (= delta(delta G not equal to)/delta[urea])) was altered by either reduction of pH or the L-->A mutations. Thermodynamic interpretations of the changes in m not equal to urea led to a conclusion that the exposed surface area of Mb in the transition state was determined by both protein-core stability and pH conditions. We also performed urea- and acid-denaturation experiments, and gave some inspections on differences between mutational effects on the structure of the transition state and the denatured state.
authors.affiliation: Division of Molecular Engineering, Graduate School of Engineering, Kyoto University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Konno
authors.forename: I
authors.initials: I
authors.lastname: Morishima
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D006801:Humans; D007700:Kinetics; D008786:Metmyoglobin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000235:genetics; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D011489:Protein Denaturation
chemical_list: C007177:cyanometmyoglobin; D008786:Metmyoglobin