Effect of phytic acid and buffer ions on recombinant human lysozyme purification

Recombinant human lysozyme derived from transgenic rice requires an optimized single chromatography step process to produce an economically viable product for low cost applications. Developing a process with a single chromatography step requires careful consideration of the compatibility of the extraction conditions with the subsequent purification step and optimization of processing conditions. Therefore, identifying and understanding critical rice extract components and their interactions are imperative to designing an optimized process. In our previous work, we found that the conditions which gave the highest purity significantly reduced the cation exchange binding capacity. We speculate that phytic acid was primarily responsible for the unacceptably low capacity. Phytic acid is known to form binary and tertiary complexes with proteins. In addition, our data suggests that phytic acid also affects the extraction efficiency of human lysozyme. In this study, we evaluated alternative extraction and purification methods in an attempt to reduce the interference of phytic acid on lysozyme purification. Degrading phytic acid in extracts using phytase enzyme and using buffer ions that minimize phytic acid interactions were effective alternative methods. Besides phytic acid, we also found that phosphate salts and extraction buffer ions can affect human lysozyme purification by cation exchange chromatography.

Effect of phytic acid and buffer ions on recombinant human lysozyme purification Conference Paper