rHSA–rhGH Conjugation With EMCS for Long-Acting Growth Hormone
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Solution Overview
Problem
The short half-life of recombinant human growth hormone (rhGH) due to high clearance in the body necessitates daily injections, which is inconvenient and costly for long-term treatments, and existing fusion expression methods result in degradation, low expression levels, and reduced biological activity.
Innovation Solution
Conjugation of recombinant human serum albumin (rHSA) with rhGH using a linker group, specifically N-succinimidyl 6-maleimidohexanoate (EMCS), followed by a multi-step purification process involving dextran gel, hydrophobic, and anion chromatography to form a stable, long-acting conjugate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If rhGH is administered directly by injection, then the therapeutic effect can be achieved when plasma concentration is reached, but the half-life is short due to high clearance requiring daily injections
Solution Approach 1:
The patent combines rhGH with rHSA through chemical conjugation to form an rHSA-rhGH conjugate. This merging of two proteins creates a new molecular entity that leverages the long circulation properties of albumin while maintaining the therapeutic activity of growth hormone, thereby extending half-life and reducing dosing frequency from daily to less frequent administrations
Solution Approach 2:
The invention creates a composite protein structure consisting of rHSA and rhGH linked together. This composite material combines the beneficial properties of both components: the stability and long circulation of albumin with the therapeutic function of growth hormone, achieving sustained release and reduced clearance
2Productivity
If fusion expression method is used to create long-acting growth hormone, then the expression level can be improved, but the protein is prone to degradation and biological activity is reduced
Solution Approach 1:
Instead of creating a single fused protein through genetic engineering, the patent segments the long-acting growth hormone into two separate components (rHSA and rhGH) that are chemically linked. This segmentation allows each component to maintain its native structure and function while achieving the long-acting effect through the conjugate, avoiding the degradation and activity loss associated with fusion proteins
3Stability of the object's composition
If rHSA and rhGH are conjugated via EMCS linker, then a stable conjugate can be formed, but the purification process becomes complex requiring multiple chromatography steps
Solution Approach 1:
The purification process is segmented into multiple sequential chromatography steps, each targeting specific impurities or conjugate forms. This segmentation allows for systematic removal of unreacted materials, side products, and incomplete conjugates, achieving high purity through a series of specialized separation operations rather than a single complex step
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
The rHSA-rhGH conjugate achieves a long-acting effect with high purity (>95%) and good biological activity, allowing for less frequent dosing and reducing medical costs.
Implementation Method 1
The NHS ester terminus is conjugated with a primary amine at pH 7-9 to form a stable amide bond
Implementation Method 2
maleimide is reacted with -SH group at pH 6.5-7.5 to form a stable thioether bond
Implementation Method 3
subjecting the conjugate to separation and purification
Implementation Method 4
a multi-step purification process involving dextran gel, hydrophobic, and anion chromatography
Implementation Method 5
a multi-step purification process involving dextran gel, hydrophobic, and anion chromatography
Data Source
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AI summary
A stable long-acting growth hormone that uses recombimant human serum albumin and recombinant humal growth hormone as ingredients and is formed by means of linker conjugation, as well as a preparation method therefor. An rHSA-hGHconjugate having a purity not lower than 95% is obtained after separation and purification.