rHSA Extraction from Transgenic Rice Grain
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Solution Overview
Problem
Current methods for producing recombinant human serum albumin (rHSA) face challenges such as insufficient plasma supply, risk of infectious pathogens, and high production costs, with existing expression systems not suitable for industrialized production due to low expression levels.
Innovation Solution
A method for extracting rHSA from transgenic rice grain involves removing the hull, grinding, and mixing with a specific extraction buffer, followed by pH adjustment and precipitation to enhance extraction efficiency and reduce non-target proteins, utilizing a combination of phosphate buffer, sodium acetate, ammonium sulfate, and sodium caprylate, and heat treatment to achieve high yields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HSA is extracted from human plasma, then the product can be obtained with high purity, but the plasma supply is insufficient and there is risk of infectious pathogens
Solution Approach 1:
The patent extracts the target protein HSA from a plant-based source (rice endosperm) rather than from human plasma. The transgenic rice grain serves as a bioreactor that accumulates HSA in its protein bodies, allowing extraction of the protein without using human blood plasma, thus eliminating pathogen risk while providing sufficient quantity through agricultural production
Solution Approach 2:
The patent uses transgenic rice grain as a disposable, renewable source of HSA. Rice can be cultivated annually on a large scale, providing a sustainable and cost-effective alternative to plasma donation. The rice grain serves as a single-use bioreactor that can be processed to extract HSA, then replaced with new crop cycles
2Productivity
If conventional expression systems (prokaryotes, yeasts, animal cells) are used to produce rHSA, then production can be scaled, but the expression level is low and production cost is high
Solution Approach 1:
The patent utilizes the unique structure of rice endosperm cells, specifically the protein bodies, as specialized storage compartments for HSA. The endomembrane system and protein bodies of rice endosperm provide a localized environment that supports high-level HSA accumulation, achieving expression levels above 0.3% of seed weight, which is superior to conventional expression systems
Solution Approach 2:
The patent employs specific promoters and signal peptides that are optimized for rice endosperm expression to dramatically increase HSA production levels. By changing the biological parameters (promoter strength, signal peptide sequence) and the physical environment (rice endosperm matrix), the system achieves high expression levels that reduce production costs while maintaining scalability
3Ease of operation
If simple extraction methods are used for rHSA from rice grain, then the process is easy to operate, but the extraction efficiency is low and non-target proteins are not sufficiently reduced
Solution Approach 1:
The patent exploits phase transition of proteins based on their isoelectric points. By adjusting the pH of the extraction buffer to 4.0-4.5, which is near the isoelectric point of HSA (pI 4.7-4.9), the protein undergoes a phase transition from soluble to precipitated state, enabling selective precipitation of HSA while keeping other proteins in solution. This simple pH adjustment dramatically improves extraction efficiency and purity
Solution Approach 2:
The patent uses a multi-parameter extraction buffer system that optimizes several conditions simultaneously: pH (6.5-8.0 for extraction, then adjusted to 4.0-4.5 for precipitation), ionic strength (ammonium sulfate), and temperature (heat treatment). These parameter changes enable high-efficiency extraction of HSA while precipitating non-target proteins, achieving both simplicity and high productivity
Data Source
AI summary
A method for extracting recombinant human serum albumin (rHSA) from transgenic rice grain is provided, comprising the steps of: 1) grinding dehusked rice containing rHSA into milled rice grain with a fineness of 80˜120 mesh, which is mixed with a extraction buffer in a w/v ratio of 1:5, then extracting at 55˜60° C. for 1˜3 hours to obtain mixture I; said extraction buffer comprises 10˜30 mM phosphate buffer, 10˜20 mM sodium acetate, 15˜30 mM ammonium sulfate and 5˜20 mM sodium caprylate and has a pH of 6.5˜8; 2) adjusting the pH of mixture I to 4.0˜4.5, followed by precipitating at room temperature for 3˜12 hours to obtain mixture II; 3) filtering the mixture II and collecting the filtrate, to obtain a solution containing high concentration of rHSA. The concentration of rHSA in the resultant solution is 650˜660 μg/mL, which increases by 1.15 times comparing to the extraction amount before improvement, and the amount of non-target protein is reduced by 2.46 times. The method provides a basis for subsequent purification of rHSA.