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
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:14 p.m.
|Number of data points||15|
|Assays/Quantities/Protocols||Experimental Assay: Cm ; Experimental Assay: m ; Experimental Assay: dG_H2O ; Derived Quantity: ddG_H2O|
|Libraries||Mutations for sequence MGLSDGEWQLVLNVWGKVEADIPGHGQEVLIRLFKGHPETLEKFDKFKHLKSEDEMKASEDLKKHGATVLTALGGILKKKGHHEAEIKPLAQSHATKHKIPVKYLEFISECIIQVLQSKHPGDFGADAQGAMNKALELFRKDMASNYKELGFQG|