Spider Silk Protein Polymerization via pH and Ion Control
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Solution Overview
Problem
The production of recombinant spider silk proteins is challenging due to their highly repetitive nature, leading to transcription and translation errors, protein aggregation, and instability in microbial expression systems, making it difficult to maintain them in a soluble form and form polymers or fibers effectively.
Innovation Solution
A method involving a spider silk protein comprising an N-terminal fragment, a repetitive fragment, and an optional C-terminal fragment, controlled by pH and ion composition to prevent or allow polymerization, enabling the production of water-soluble proteins that can readily form fibers under physiological conditions, avoiding toxicity and protein denaturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spider silk proteins are produced recombinantly in microbial expression systems, then production scalability is improved, but protein aggregation and precipitation occur leading to loss of soluble protein
Solution Approach 1:
The spider silk protein is divided into separate functional domains: an N-terminal domain that maintains solubility and a C-terminal domain that promotes polymerization. This segmentation allows the protein to be expressed in soluble form and then controlled to polymerize only when needed, resolving the contradiction between scalability and solubility.
Solution Approach 2:
The patent uses pH and ionic strength as controllable parameters to regulate protein polymerization. By adjusting these parameters, the protein can be maintained in soluble form during production and then induced to polymerize under controlled conditions, enabling both scalable production and reliable solubility control.
2Stability of the object's composition
If spider silk proteins are maintained in soluble form, then protein stability is improved, but polymerization and fiber formation are inhibited
Solution Approach 1:
The protein is pre-expressed in soluble form with the polymerization capability already present but inactive. This preliminary soluble state allows for stable production and purification, after which polymerization is induced by changing environmental conditions such as pH or ionic strength.
Solution Approach 2:
The patent creates a dynamic system where the protein can transition between soluble and polymerized states based on environmental conditions. This dynamic control allows optimization of each stage: soluble state for production and stable state for fiber formation.
3Reliability
If conventional solubilization methods using non-physiological solvents are used, then protein solubility is improved, but protein denaturation and loss of native structure occur
Solution Approach 1:
Instead of using harsh non-physiological solvents, the patent uses gentle parameter changes in pH and ionic strength to control solubility and polymerization. This maintains the protein in its native conformation throughout the process, preserving structural integrity while achieving the desired solubility and polymerization states.
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 method allows for the controlled production of spider silk polymers and fibers with desirable properties, such as high strength and elasticity, suitable for medical and technical applications, without the need for harsh solvents or cleavable fusion partners, facilitating industrial-scale production.
Implementation Method 1
the repetitive region undergoes a structural conversion from random coil and α-helical conformation to β-sheet structure
Implementation Method 2
adjusting the properties of said liquid medium to a pH of 6.3 or lower and an ion composition that allows polymerisation of said spider silk protein
Implementation Method 3
an ion composition that prevents polymerisation of said spider silk protein
Data Source
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AI summary
A method of producing polymers of an isolated spider silk protein involves providing a solution of said spider silk protein in a liquid medium at p H 6.4 or higher and/or an ion composition that prevents polymerisation of the spider silk protein. The properties of the liquid medium are adjusted to a pH of 6.3 or lower and an ion composition that allows polymerisation of the spider silk protein. The spider silk protein is allowed to form polymers in the liquid medium, and the resulting spider silk protein polymers are isolated from the liquid medium. The resulting polymers are useful as fibers, films, foams, nets or meshes.