Characterization of major stable proteins in chardonnay wine

Abstract

Chardonnay wine produced in the conventional manner contained 69.8 to 108mg/L soluble proteins including nondialyzable polypeptides; with an average of 87.2 mg/L. Proteins were separated by precipitation with ammonium sulfate, and fractionated into two fractions, F1 (mainly invertase and proteoglycans) and F2 (glycoproteins), by Sephadex G-100 column chromatography. The fractions were further separated by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) [isoelectric focusing and SDS-polyacrylamide gel electrophoresis]. More than 160 and 150 protein spots were detected on the 2-D PAGE maps of F1 and F2, respectively. The major proteins or polypeptides were determined to be fruit proteins, such as thaumatin- and osmotin-like proteins, invertase, lipid transfer protein (LTP), and their hydrolysis products. This is first report on the existence of LTP (or its hydrolysis product) and the hydrolysis products of major grape proteins (invertase, osmotin-like protein, and thaumatin-like protein) in wine.