ARS | Publication request: Transglutaminase Polymerization of Peanut Proteins

Submitted to: World Congress of International Union of Food Science and Technology
Publication Type: Proceedings
Publication Acceptance Date: July 15, 2007
Publication Date: July 16, 2007
Citation: Clare, D.A., Gharst, G., Sanders, T.H. 2007. Transglutaminase Polymerization of Peanut Proteins. World Congress of International Union of Food Science and Technology.

Technical Abstract: INTRODUCTION: Transglutaminase (TGase) [protein-glutamine:amine gamma-glutamyl-transferase, EC 2.3.2.13]promotes protein cross-linking reactions through an acyl transferase mechanism involving protein-bound glutaminyl residues and primary amines (1), including the epsilon-amino group of lysine residues in proteins such as soy, myosin, gluten, oat globulin, casein and whey (2,3,4). Herein, we present a first report of TGase catalysis of protein fractions prepared from peanut, Arachis hypogaea L, and the effects of polymerization on stated experimental parameters. OBJECTIVES: This study was focused on characterizing the effects of covalent crosslinking reactions, catalyzed by microbial transglutaminase (mTGase), on (i) peanut protein (PP) solubility, (ii) SDS-PAGE protein and glycoprotein banding patterns, (iii) the degree of crosslinking, and (iv) IgE reactivity with polymerized PP fractions. METHODS: SDS-PAGE electrophoresis, o-Phthaldialdehye (OPA) analyses, and enzyme linked immunosorbent(ELISA) assays were accomplished according to standard procedures. PP-carbohydrate coupling was observed using a glycoprotein staining kit while protein solubility was measured with bicinchoninic acid (BCA) methodologies. RESULTS: mTGase-crosslinking of whole PP extracts, and Ara h1, a purified PP preparation, was monitored over several hours. The resultant SDS-PAGE and glycoprotein banding pattern of enzyme treated PP fractions showed a ”smear” of higher molecular weight species while polymerization of Ara h1 produced distinct dimer formation. OPA assays revealed approximately 20% coupling after incubation of PP fractions with mTgase for >3h at 37 degrees C. IgE responses, an indicator of potential allergic reactions, were measured for all PP test samples using ELISA protocols. These results showed slightly elevated IgE binding to PP polymers as compared to non-crosslinked PP fractions. CONCLUSIONS: To our knowledge, this study provides a first report of PP polymerization by mTGase. Crosslinking did not diminish IgE binding responses as detected by ELISA measurements.