Incorporation of Tryptophan Analogues into Staphylococcal Nuclease: Stability toward Thermal and Guanidine-HCl Induced Unfolding†

摘要: The tryptophan analogues, 5-hydroxytryptophan, 7-azatryptophan, 4-fluorotryptophan, 5-fluorotryptophan, and 6-fluorotryptophan, have been biosynthetically incorporated into Staphylococcal nuclease, its V66W mutant, the Δ137−149 fragment of latter mutant. guanidine−HCl induced unfolding thermal these proteins were studied to characterize effect incorporation analogues on thermodynamic stability proteins. three residues at positions 140 (in wild type) 66 V66W) both V66W). data show that 5-hydroxytryptophan does not perturb wild-type but it destabilizes causes mutant unfold in a more cooperative manner. 7-Azatryptophan is found destabilize all 4-Fluorotryptophan slightly stabilizing proteins, other two fluorotryptophans do alter ...