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Why do crown ethers activate enzymes in organic solvents?
Dirk-Jan van Unen1, Johan F J Engbersen, David N Reinhoudt
1Laboratory of Supramolecular Chemistry and Technology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands.
Biotechnology and Bioengineering
|December 26, 2001
Summary
Crown ethers significantly enhance enzyme activity in organic solvents by altering enzyme conformation. This effect, particularly strong after lyophilization, involves both macrocyclic interactions and a larger nonmacrocyclic lyoprotection effect.
Area of Science:
- Biochemistry
- Biocatalysis
- Enzyme Engineering
Background:
- Enzymes exhibit reduced activity in nonaqueous solvents compared to aqueous environments.
- Crown ether treatment offers a method to overcome this limitation and enhance enzyme performance.
Purpose of the Study:
- To elucidate the mechanisms behind crown ether activation of enzymes in organic solvents.
- To investigate the role of macrocyclic interactions and lyoprotection in enzyme activity enhancement.
Main Methods:
- Designed experiments to study crown ether activation of enzymes.
- Utilized 18-crown-6 for enzyme treatment in organic solvents.
- Analyzed enzyme activity post-crown ether removal and lyophilization.
Main Results:
- 18-crown-6 enhances enzyme activity by reducing salt bridges and conformational barriers.
- Enhanced activity is retained after crown ether removal.
- Pre-lyophilization addition of 18-crown-6 yields stronger activation due to combined effects.
- Nonmacrocyclic lyoprotection contributes more significantly than macrocyclic refolding.
Conclusions:
- Crown ether activation involves specific macrocyclic interactions and broader lyoprotective effects.
- The nonmacrocyclic lyoprotection effect is a dominant factor in enzyme activity enhancement.
- Optimal activation is observed in dry, apolar solvents where kinetic barriers are highest.