Stabilization of myoglobin by multiple alanine substitutions in helical positions.


We have carried out a series of multiple Xaa-->Ala changes at nonadjacent surface positions in the sequence of sperm whale myoglobin. Although the corresponding single substitutions do not increase the thermal stability of the protein, multiple substitutions enhance the stability of the resulting myoglobins. The effect observed is an increase in the observed Tm (midpoint unfolding temperature) relative to that predicted from assuming additivity of the free energy changes corresponding to single mutations. The stabilization occurs in the presence of urea, as measured by the dependence of the unfolding temperature on urea concentration. The sites that have been altered occur in different helices and are not close in sequence or in the native structure of myoglobin. The observed effect is consistent with a role of multiple alanines in residual interactions in the unfolded state of the mutant proteins. Study holds ProTherm entries: 10139, 10140, 10141, 10142, 10143, 10144, 10145, 10146, 10147, 10148, 10149, 10150, 10151, 10152, 10153, 10154, 10155, 10156, 10157, 10158, 10159, 10160, 14518, 14519, 14520, 14521, 14522, 14523, 14524, 14525, 14526, 14527, 14528, 14529, 14530, 14531, 14532, 14533, 14534, 14535, 14536, 14537, 14538, 14539 Extra Details: 0.5 mM of KCN as additive alpha-helix; protein folding; protein stability;,sperm whale myoglobin

Submission Details

ID: 9fa7Dws84

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:39 p.m.

Version: 1

Publication Details
Lin L;Pinker RJ;Phillips GN;Kallenbach NR,Protein Sci. (1994) Stabilization of myoglobin by multiple alanine substitutions in helical positions. PMID:7833805
Additional Information

Sequence Assay Result Units