Protein stabilization and destabilization by guanidinium salts.

Area of Science:

• Biochemistry
• Protein Chemistry
• Chemical Thermodynamics

Background:

• Proteins are sensitive to their solution environment.
• Salts can alter protein structure and function through various interactions.
• Understanding these interactions is crucial for protein stability and drug development.

Purpose of the Study:

• To investigate the preferential interactions of bovine serum albumin (BSA) with different guanidine salts.
• To correlate these interactions with the known effects of guanidine salts on protein stability.
• To compare the effects of guanidinium ions with magnesium ions on protein hydration and salt binding.

Main Methods:

• Measurement of preferential interactions of BSA with guanidine sulfate, guanidine acetate, and guanidine hydrochloride.
• Analysis of hydration and salt binding based on concentration-dependent interactions.
• Comparison with existing data on protein stability and interactions with magnesium salts.

Main Results:

• Guanidine sulfate showed increasing preferential hydration with concentration.
• Guanidine hydrochloride exhibited positive preferential salt binding.
• Guanidine acetate presented an intermediate interaction profile.
• Guanidinium ions decreased preferential hydration and increased salt binding compared to Mg2+.

Conclusions:

• Guanidine salts' effects on proteins are governed by a balance of hydration and salt binding.
• The observed protein stabilization by guanidine sulfate and denaturation by guanidine hydrochloride correlate with these interactions.
• Guanidinium ions have a stronger effect on protein surface free energy perturbation than Mg2+ ions.