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Exploiting Phytic Acid-Protein Interactions for Purification of a Rice-Derived Recombinant Protein
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org
Citation: 2026 ASABE Annual International Meeting 2600197.(doi:10.13031/aim.202600197)Authors: Lisa R. Wilken, Reagan E. Gomez, Dr.
Keywords: Recombinant human serum albumin (rHSA), phytic acid, rice protein, purification
Abstract. Human serum albumin (HSA) is a blood protein that supports cell growth and viability in culture media; enhances the stability of cells, vaccines and proteins; and improves delivery of drugs or metabolites due to its ligand binding capabilities. According to Verified Market Research (2025), global demand for HSA is projected to reach $7.4 billion by 2031. Various production systems, such as genetically modified yeast, bacteria, rice, and tobacco, have been leveraged as alternatives to overcome limitations of blood-sourced HSA. Advantages of using terrestrial plants include having established agricultural infrastructure and eliminating the risk of human pathogen transmission. Rice is also generally regarded as safe (GRAS) and capable of high expression levels. Chromatography is the primary method for purification of plant-derived rHSA, but the high operational and material costs limit its use, particularly for lower value applications. Thus, innovative solutions are needed for broader utility of rice-derived HSA. This work investigates the use of a novel method that harnesses the binding capabilities of HSA and the native rice impurity, phytic acid, to induce precipitation for rHSA purification. Phytic acid (PA) is an abundant phosphate storage compound which is negatively charged above pH 1.3. PA is often considered an antinutrient due to its ability to form protein-PA and protein-cation-PA complexes, reducing bioavailability. However, this work repurposes PA as a separation agent to selectively precipitate rHSA, rebranding the antinutrient and waste product as a functional and readily available purification tool. Our previous research identified PA concentration and pH as two critical factors influencing the extent of protein precipitation. This study assesses the impact of these factors on the effectiveness and selectivity of PA-induced precipitation of rHSA from clarified rice extract. The rHSA and total soluble protein (TSP) concentrations were determined by SEC-UPLC and Bradford Protein Assay, respectively, along with the dry mass and used to determine rHSA yield, purity, and % composition of the dry mass.
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