Salt hydrates buffer water activity during chymotrypsin-catalysed peptide synthesis

Area of Science:

• Biocatalysis
• Organic Chemistry
• Enzyme Engineering

Background:

• Enzyme-catalyzed reactions in organic solvents often face challenges with water activity control.
• Maintaining optimal water levels is crucial for both enzyme activity and preventing unwanted side reactions like hydrolysis.
• Chymotrypsin is a serine protease with known catalytic capabilities.

Purpose of the Study:

• To evaluate chymotrypsin as a catalyst for peptide synthesis in an organic solvent.
• To investigate the role of sodium carbonate decahydrate in controlling water activity for enzymatic reactions.
• To demonstrate a method for enhancing enzyme stability and activity in non-aqueous media.

Main Methods:

• Chymotrypsin powder was suspended in hexane.
• Sodium carbonate decahydrate (Na2CO3.10H2O) was added to the reaction mixture.
• Peptide synthesis was performed under these conditions.
• Water activity was monitored and controlled via the salt hydrate's dissociation pressure.

Main Results:

• Chymotrypsin demonstrated good catalytic activity for peptide synthesis in hexane.
• The presence of Na2CO3.10H2O effectively buffered the system's water activity.
• Hydrolytic side reactions were minimized, leading to improved synthesis efficiency.

Conclusions:

• Salt hydrates, specifically sodium carbonate decahydrate, are effective tools for buffering water activity in organic solvent-based enzyme reactions.
• This method allows for optimized chymotrypsin activity in peptide synthesis while suppressing hydrolysis.
• The findings suggest a practical approach for utilizing enzymes in organic synthesis with enhanced control and efficiency.