Biodegradable Copolymer Production via Enzymatic Polymerization
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Solution Overview
Problem
Current methods for producing high molecular weight polylactate (PLA) are complex and involve solvents or chain coupling agents, while PHA synthase has limited activity on lactyl-CoA and hydroxyalkanoates hydroxylated at the 2-position, making it difficult to produce copolymers with these monomers effectively.
Innovation Solution
A method involving the culture of cells or plants with specific genes for enzymes that convert lactate and 3-hydroxyalkanoates into lactyl-CoA and 3-hydroxyalkanoyl-CoA, combined with phosphotransbutylase and butyrate kinase genes, to produce copolymers comprising 4-hydroxybutyrate, lactate, and 3-hydroxyalkanoate monomers units, such as 4-hydroxybutyrate-lactate copolymers or terpolymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If direct polymerization of lactate is used to produce PLA, then the process is simple, but only low molecular weight PLA (1000-5000 dalton) is produced
Solution Approach 1:
The patent uses an enzyme (PHA synthase) as a mediator to enable direct polymerization of lactate into high molecular weight PLA. The enzyme acts as a biological catalyst that facilitates the polymerization reaction without requiring complex chemical reagents or multiple processing steps, thus maintaining process simplicity while achieving high molecular weight products.
2Quantity of substance
If chain coupling agent is added to synthesize high molecular weight PLA, then high molecular weight PLA (>100,000 dalton) can be produced, but the process becomes complicated and it is difficult to remove the coupling agent
Solution Approach 1:
The patent replaces the mechanical/chemical approach of using chain coupling agents with a biological approach using enzymatic polymerization. The PHA synthase enzyme naturally catalyzes the formation of high molecular weight PLA without requiring external coupling agents, thereby eliminating the complexity of adding and removing chemical reagents while achieving the desired molecular weight.
3Reliability
If PHA synthase is used to synthesize PHA, then biodegradable polymer is produced, but PHA synthase has little activity on hydroxyalkanoate hydroxylated at the 2-position (lactyl-CoA)
Solution Approach 1:
The patent modifies the substrate parameters by using modified PHA synthase enzymes that have altered substrate specificity. These modified enzymes can accept lactyl-CoA and other 2-hydroxyalkanoates as substrates, which the wild-type enzymes cannot efficiently process. This parameter change in enzyme substrate affinity enables the production of biodegradable copolymers containing lactate and other 2-hydroxyalkanoate units.
4Adaptability or versatility
If conventional methods are used to produce copolymers with lactate and 3-hydroxyalkanoate, then the process requires multiple enzymes and complex metabolic pathways, but the production efficiency is low
Solution Approach 1:
The patent combines multiple enzyme functions into a single PHA synthase enzyme that can polymerize multiple different monomers (lactate, 3-hydroxyalkanoates, and other 2-hydroxyalkanoates) simultaneously. This merging of substrate specificity into one enzyme simplifies the metabolic pathway and eliminates the need for separate polymerization systems for different monomers, thereby improving production efficiency while maintaining copolymer versatility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for the efficient production of biodegradable copolymers that can be used as alternatives to conventional plastics, overcoming the limitations of existing PLA production methods and PHA synthase activity, and enabling the synthesis of polymers with desired monomer units.
Implementation Method 1
PHA synthase synthesizes PHA using hydroxyacyl-CoA as a substrate
Implementation Method 2
alpha-ketothiolase (PhaA), acetoacetyl-CoA reductase (PhaB), cloned from Ralstonia eutropha etc., 3-hydroxydecanoyl-ACP:CoA transferase (PhaG) cloned from Pseudomonas sp.
Data Source
Figure 1~2
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AI summary
The present invention relates to a copolymer comprising 4-hydroxybutyrate monomer unit and lactate monomer unit, a copolymer 4-hydroxybutyrate monomer unit, lactate monomer unit and 3-hydroxyalkanoate, or their preparing method. More specifically, the present invention relates to a method for preparing a copolymer comprising lactate monomer; 4-hydroxybutyrate monomer; and optionally 3-hydroxyalkanoate, wherein the method comprises culturing a cell or plant comprising the gene of enzyme converting lactate and 3-hydroxyalkanoate into lactyl-CoA and 3-hydroxyalkanoyl-CoA, respectively, phosphotransbutylase gene, butyrate kinase gene and polyhydroxyalkanoate synthase gene together, and the copolymer made by the method. The copolymer of the present invention is a biodegradable polymer being able to be usefully used instead of conventional synthetic plastic, and the copolymer can be used for medical use.