Mutagenesis study for understanding the superabsorbent behavior of patatin-based protein materials

Protein-based absorbent materials exhibit significant limitations in water retention compared to synthetic superabsorbent polymers (SAPs), widely used in agriculture, hygiene, and biomedical applications. Recent investigations have focused on leveraging highly soluble charged proteins such as patatin (a glycoprotein derived from potatoes) as natural alternatives to synthetic SAPs, given their unique structural properties and the opportunity they provide as sustainable raw material alternatives. This study investigates how the intrinsic amino acid composition and charged residues of patatin can be modified through mutagenesis to tailor its superabsorbent properties. Here, patatin was expressed in Escherichia coli to improve the water absorption capacity by altering its amino acid composition. By increasing liquid accessibility and charge density, our method of altering the charged profile of the protein significantly enhances the protein's swelling capacity, doubling its absorption compared to native patatin. Additionally, molecular dynamics simulations reveal that protein variants enriched with lysine and aspartic acid facilitate increased hydrogen bonding interactions with water molecules, thereby enhancing hydration. These results provide a fundamental understanding of how to tailor the physicochemical nature of proteins to develop them as viable bio-based absorbents for advanced sanitary applications, combining material science and biotechnology.