Transition state of an unfolding step in human cyanomet myoglobin.


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. Study holds ProTherm entries: 203, 204, 205, 206 Extra Details: NaCN(0.5 mM) was added in the experiment human cyanomet myoglobin; absorption spectroscopy; transition state;,mutational effects; protein-core stability

Submission Details

ID: uxTm2NKh

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:14 p.m.

Version: 1

Publication Details
Konno T;Morishima I,Biochim. Biophys. Acta (1993) Transition state of an unfolding step in human cyanomet myoglobin. PMID:8448200
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