Valine 108, a Chain-Folding Initiation Site-Belonging Residue, Crucial for the Ribonuclease A Stability

The effect of additional disulfide bonds on the stability and folding of ribonuclease A

“…The folding region of RNase A had been postulated for residues 106-118 ( Fig. 1; [22]) and its importance for the folding and stability of the RNase A molecule has been confirmed by mutagenesis studies [23] or replacement of cisPro114 by the cis-locked β-turn mimic 5',5'-dimethylproline [24]. As for the unfolding process, the section from the C-terminal end of helix II (Lys31) through the first β-sheet strand (Phe46) became susceptible first to proteolytic attack by thermolysin and trypsin under denaturing conditions [25] and several residues in this region showed a faster H-D exchange than that of global unfolding [26,27].…”

Genetic Selection for Critical Residues in Ribonucleases

“…It had been shown that Ile106 is important in RNase A, as its replacement with alanine lowers the T m value of the enzyme by 14 deg.C. 91 The importance of Ser75 had not been demonstrated, though other workers had suggested that Ser75 could be important for the conformational stability of RNase A. 22,23 Replacing Ser75 or Ile106 allows for growth in our selection system.…”

“…89,90 A V108G substitution is known to decrease the conformational stability of RNase A substantially. [89][90][91] Substitutions at Tyr73 or Val108 enable isolation with our selection system.…”

Thermal stability and enzymatic activity of RNase A in the presence of cationic gemini surfactants

“…Recently, the importance of hydrogen bonding has become clear. Studies of mutant proteins have improved our understanding of the forces stabilizing proteins [7][8][9][10][11]. Overall, the conformational stability of a protein is defined as the free energy change, G, for the equilibrium between the native state and the denatured state ensemble under physiological conditions [12,13].…”