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Poly(3-hydroxybutyrate)-depolymerase from Pseudomonas lemoignei: catalysis of esterifications in organic media
A Kumar1, R A Gross, D Jendrossek
1Department of Chemical Engineering, Chemistry and Material Science, Polytechnic University, Brooklyn, New York 11201, USA.
The Journal of Organic Chemistry
|November 14, 2000
Summary
Polyhydroxyalkanoate depolymerase from Pseudomonas lemoignei catalyzes ester-forming reactions in organic solvents. This enzyme shows selectivity for various lactones and can polymerize epsilon-caprolactone and trimethylene carbonate.
Area of Science:
- Biocatalysis
- Polymer Chemistry
- Enzyme Engineering
Background:
- Lipase catalysis in nonaqueous media is crucial for organic and polymer synthesis.
- Polyhydroxyalkanoate (PHA) depolymerases share catalytic similarities with lipases, despite lacking direct lipase activity.
- The poly(3-hydroxybutyrate) (PHB) depolymerase from Pseudomonas lemoignei presents an unexplored potential for ester-forming reactions.
Purpose of the Study:
- To investigate the potential of PHB depolymerase from P. lemoignei in catalyzing ester-forming reactions within organic media.
- To evaluate the influence of solvent polarity on the enzyme's activity during the propylation of L-lactide.
- To determine the selectivity of PHB depolymerase towards various lactones and stereochemically distinct lactic acid dimers.
Main Methods:
- Enzymatic catalysis using PHB depolymerase from P. lemoignei.
- Reactions conducted in different organic solvents including benzene-d(6), cyclohexane-d(12), and acetonitrile-d(3).
- Assessment of enzyme activity and selectivity across a range of lactones (epsilon-caprolactone, delta-butyrolactone, gamma-butyrolactone) and lactides (D, L, meso, racemic).
- Investigation of solventless polymerization of epsilon-caprolactone and trimethylene carbonate.
Main Results:
- Significant variations in catalytic rates were observed based on solvent polarity during L-lactide propylation.
- PHB depolymerase exhibited distinct reactivity patterns with different lactones and selective hydrolysis of stereoisomers of lactic acid dimers.
- The enzyme demonstrated the capability to catalyze solventless polymerization of epsilon-caprolactone and trimethylene carbonate.
Conclusions:
- P. lemoignei PHB depolymerase is a versatile biocatalyst for ester-forming reactions in nonaqueous media.
- Solvent choice critically impacts the enzyme's catalytic efficiency and substrate selectivity.
- The enzyme holds promise for green polymer synthesis, including the polymerization of cyclic esters and carbonates.