To investigate the contribution to protein stability of electrostatic interactions between charged surface residues, we have studied the effect of substituting three negatively charged solvent exposed residues with their side-chain amide analogs in bovine calbindin D9k--a small (Mr 8,500) globular protein of the calmodulin superfamily. The free energy of urea-induced unfolding for the wild-type and seven mutant proteins has been measured. The mutant proteins have increased stability towards unfolding relative to the wild-type. The experimental results correlate reasonably well with theoretically calculated relative free energies of unfolding and show that electrostatic interactions between charges on the surface of a protein can have significant effects on protein stability. Study holds ProTherm entries: 2512, 2513, 2514, 2515, 2516, 2517, 2518, 2519 Extra Details: additive : EDTA(0.3 mM),ddG was measured in the presence of 5M urea urea induced unfolding; increased stability; calbindin D9k;,site-directed mutagenesis
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:19 p.m.