(425i) Purification and Characterization of a Recombinant Gelatin Expressed in Transgenic Maize

Gelatins are widely used in pharmaceutical capsules. Currently, those materials are made from denatured collagens, mainly produced from bovine or porcine skins or bones . These animal-derived materials pose concerns regarding allergic reactions and animal-derived materials contamination. The lot-to-lot variability and lack of uniformity in size also prompt the development of a more consistent product. In this work we evaluate producing a safe and well-defined recombinant gelatin as a collagen fragment from transgenic maize.

To characterize the maize version, it was necessary to obtain a pure preparation. The recombinant gelatin was extracted into aqueous medium and the extract was clarified by centrifugation. The expression level of recombinant gelatin determined from the extract is about 17 mg/kg seed. Purification was carried out using a two-step process of cation exchange chromatography followed by a gel filtration chromatography. Concentration and purity were determined by ELISA, SDS-PAGE, and Western blotting. The purified recombinant gelatin was subjected to mass spectrometry to measure intact protein mass and deduce amino acid sequence. Data from N-terminal sequencing and peptide sequence and intact protein molecular weight analysis from mass spectrometry were compared to the expected mass and sequence from the genetic information. The measured mass of 44088 Da was within 0.2% of the calculated mass and measurable peptide sequences provide a 64% sequence coverage supporting fidelity of expression. Staining of gels for carbohydrate showed no detectable glycosylation.