title: Correlation of high-temperature stability of alpha-chymotrypsin with 'salting-in' properties of solution.
abstract: A correlation between the stability of alpha-chymotrypsin against irreversible thermal inactivation at high temperatures (long-term stability) and the coefficient of Setchenov equation as a measure of salting-in/out efficiency of solutes in the Hofmeister series has been found. An increase in the concentration of salting-in solutes (KSCN, urea, guanidinium chloride, formamide) leads to a many-fold decrease of the inactivation rate of the enzyme. In contrast, addition of salting-out solutes has a small effect on the long-term stability of alpha-chymotrypsin at high temperatures. The effects of solutes are additive with respect to their salting-in/out capacities; the stabilizing action of the solutes is determined by the calculated Setchenov coefficient of solution. The correlation is explained by a solute-driven shift of the conformational equilibrium between the 'low-temperature' native and the 'high-temperature' denatured forms of the enzyme within the range of the kinetic scheme put forward in the preceding paper in this journal: irreversible inactivation of the high-temperature form proceeds much more slowly compared with the low-temperature form.
authors.affiliation: Chemistry Department, M. V. Lomonosov Moscow State University, Russian Federation.
authors.lastname: Levitsky VYu
authors.forename: A A
authors.initials: AA
authors.lastname: Panova
authors.forename: V V
authors.initials: VV
authors.lastname: Mozhaev
mesh_terms: D002918:Chymotrypsin / Q000737:chemistry* / Q000378:metabolism; D004795:Enzyme Stability; D005559:Formamides / Q000494:pharmacology; D019791:Guanidine; D006146:Guanidines / Q000494:pharmacology; D006358:Hot Temperature; D007700:Kinetics; D008961:Models, Structural; D009994:Osmolar Concentration; D011487:Protein Conformation; D012996:Solutions; D013816:Thermodynamics; D013861:Thiocyanates / Q000494:pharmacology; D014508:Urea / Q000494:pharmacology
chemical_list: D005559:Formamides; D006146:Guanidines; D012996:Solutions; D013861:Thiocyanates; C031066:formamide; D014508:Urea; D002918:Chymotrypsin; D019791:Guanidine; C009941:potassium thiocyanate