Effect of compounds of the urea–guanidinium class on renaturation and thermal stability of acid-soluble collagen

Abstract

The effects of guanidinium salts in decreasing the renaturation rate and lowering the thermal stability of acid-soluble calf-skin collagen have been compared with those of formamide and urea. With the exception of guanidinium sulphate at higher concentrations, no qualitative differences were apparent in the effects of these perturbants, which thus differed only in molar activity. Activity variation in the guanidinium salts reflected a net effect resulting from additivity of cation and anion contributions. As observed in other protein systems, lyotropic activity increased in the series formamide<urea<guanidinium ion, and in the guanidinium salts in the anion order fluoride<sulphate<chloride<bromide<nitrate<iodide. Low activities of guanidinium fluoride and sulphate were attributable to counter-effects of the anions, which acted as structural stabilizers. Changes in renaturation kinetics induced by either temperature or added perturbants appeared to conform with the Flory-Weaver model for the collagen transition. Additivity and non-specificity of the observed effects are discussed with particular reference to a common mechanism involving weak, non-saturated binding of perturbants at protein peptide groups.

Effect of Sodium Chloride on Glassy and Crystalline Melting Transitions of Wheat Starch Treated with High Hydrostatic Pressure: Prediction of Solute‐induced Barostability from Nonmonotonic Solute‐induced Thermostability

“…The effects of other diluents, such as sugar-water or saltwater, on glassy and crystalline transitions of starch during the HHP treatment have not been reported. In order to explore the effects of lyotropic concentrations (high salt concentrations that are relevant for the Hofmeister series, far above the concentration region where electrostatics dominates [1][2][3][4][5]) of salt on glassy and crystalline transitions of starch during HHP treatments, wheat starch was HHP-treated in various NaCl concentrations, and the treated samples were analyzed with DSC.…”

Unraveling the Role of Hydroxyproline in Maintaining the Thermal Stability of the Collagen Triple Helix Structure Using Simulation

“…The DSC results of the collagen solution showed that the absorption peaks at 21.5 and 32.6 °C disappeared after treatment with guanidine hydrochloride (as shown in Figure ). Guanidine hydrochloride is generally characterized as a strong hydrogen bond disrupter and hence might be expected to competitively disrupt Hyp structural hydrogen bonding in proteins. , The absorption peaks of the collagen solution disappeared, which indicated that the two absorption peaks derived from the energy absorbed by hydrogen bonds were ruptured. The first absorption peak appeared at 21.5 °C, and the Δ H was 184.3 J/g.…”

Unfolding and refolding of phospholipase C from Bacillus cereus in solutions of guanidinium chloride

“…Whereas at room temperature solutions of 8 M-urea are unable to denature phospholipase C (Little, 1978), marked denaturation occurs in solutions of guanidinium chloride above about 1 M. This dif-1979 ference in effectiveness of these two denaturants seems larger than normal with the present enzyme. Normally, guanidinium chloride is about twice as effective a denaturant on a molar basis as urea (see, e.g., Russell & Cooper, 1972;Prakashi & Nandi, 1977), but with phospholipase C, the former denaturant is at least 8-fold more effective than urea. Phospholipase C from B. cereus has a very similar stability in guanidinium chloride to penicillinase from S. aureus (Robson & Pain, 1976) and it is perhaps interesting to point out the similarity between these enzymes in terms of molecular weight, helical content and lack of disulphide cross-links (Robson & Pain, 1976;Otnmss et al, 1972Otnmss et al, , 1977Little, 1978).…”