When it comes to recombinant proteins, having a robust expression system seems to be a mandatory option for scaling up. Conventionally, Human Serum Albumin (HSA) has been produced by fractionating the plasma which leads to a major drawback of limited supply. Besides, as the source of the blood for HSA separation can vary, there is a high risk of contamination of the resultant product due to prions, viruses, and other associated pathogens. This forms a major reason for exploiting the biotechnology knowledge to come up with effective technology for quality products. In recent times, a combination of recombinant DNA technology and a robust expression system has been used for the large-scale production of rHSA (Recombinant Human Serum Albumin).
The yeast-based Pichia pastoris expression system has become one of the premier options for the production of highly pure and competent recombinant proteins. The Pichia pastoris expression system has proven to be proficient due to its key features like tightly regulated promoters, respiratory over fermentative growth, and high level of human-like glycosylation. The present article takes the understanding of the Pichia pastoris expression system to the next level to help one comprehend its benefits and efficiency of resultant product- Recombinant Human Serum Albumin (rHSA).
Glycosylation
Glycosylation is a very crucial and highly regulated mechanism for the processing of secondary protein within the cells. Proper glycosylation determines the stability and functionality of the tertiary structure of protein under synthesis. The non-glycosylated property of conventional HSA created a requirement for screening multiple hosts capable of producing correct protein structure with high potential. Earlier, organisms like Escherichia coli, Bacillus subtillis, etc., have been used but they do not give efficient human-like glycosylation. However, screening of yeast-based Pichia Pastoris expression system explained its high potential in producing human-like glycosylation, highly pure and animal-origin free recombinant proteins, making it a suitable choice for researchers for the production of rHSA.
Pichia Pastoris- A potential option for rHSA
The Yeast-based Pichia Pastoris expression system is considered to be the best option for the production of recombinant human serum albumin due to easy scale-up and high purity. Additionally, the post-translation modification property of the expression system, which offers efficient proteolytic processing, protein folding, disulphide bond formation, and adept glycosylation are major reasons for considerations.
The methylotrophic yeast expression system has proven to be highly successful in rHSA production since they produce correctly folded tertiary protein structure which is secreted into the medium directly thus easing the extraction process. The P. pastoris system secretes a very minimal level of endogenous proteins as the culture medium supporting its growth does not contain any added protein. Hence, the secreted heterologous protein will consist majorly of the total protein in the culture medium. There are many such advantages of the P. pastoris expression system which makes the production of our rHSA highly efficient:
- Synthesis of complex tertiary structures: The P. pastoris expression system has the eukaryotic sub-cellular machinery which supports the post-translation modification of the resultant product.
- Very high success rate: Since the system is capable of secreting the resultant product in the medium, there is a high success rate of getting high quality, active and functional recombinant products.
- Efficient and fast: When compared with any other expression system the growth rate of P. pastoris expression system is quite effective. Thus, expressing a sufficient amount of the recombinant protein with a high yield per volume.
- Feasibility in purification: The major advantage of producing rHSA using P. pastoris system is the high purity it offers. This is mainly due to the secretion of protein into the culture medium, aiding the chromatography process at the later stages.
- Easy scale-up: The industrial production of the recombinant protein has been limited due to the unavailability of any stable expression system. However, the introduction yeast-based expression system, specifically P. pastoris has allowed easy scale-up due to the stability, reproducibility of the process, and enhanced production rate.
- Regulatory approval: The P. pastoris expression system is well-proven and widely accepted by regulatory agencies for the production of recombinant proteins. As the resultant product is free of any endotoxins and virus contamination.
In the ever-emerging biosimilar world, no one can deny the potential of yeast-based expression system to get highly pure and animal-origin free products. We at Lazuline have exploited this potential and are using it for the production of our flagship rHSA product-rALBLAZTM. The expression system has offered us to scale up the production in bioreactors in a highly efficient and cost-effective manner. Our products are tested and approved by reputed institutions and large global organizations for end-use. To know more about our rHSA, feel free to connect with us.
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Authors:
Dr Ramesh Bhagam
Vice President-Quality Control at Lazuline Biotech
