PURIFICATION AND PARTIAL BIOCHEMICAL-CHARACTERIZATION OF GLYCOPROTEINS IN A CHAMPENOIS CHARDONNAY WINE

Seven proteins have been isolated from a champenois Chardonnay-still w ine by concanavalin A affinity chromatography. The proteins of 24/25, 30 and 60/64 kDa are then purified by preparative isoelectric focusing (pH gradient 2.5-5) and by preparative SDS-PAGE. The 30 kDa protein p resents a low hydrophobicity (780 cal/amino acid residue), a homogeneo us molecular weight, and an isoelectric point close to 2.5. It also ha s the characteristic of being retained by Lens culinaris agglutinin (L CA). Proteins of 24/25 and 60/64 kDa present heterogeneous MW, a pI cl ose to 3.9, and a hydrophobicity 30% superior to that of the 30 kDa mo lecule. Moreover, these two proteins are not retained by LCA. The thre e analyzed proteins are not susceptible to O-glycosidase activities. I n return, the 24/25 kDa protein undergoes a 3100 Da variation after tr eatment with the peptide-N-glycanase F: it is a true, N-glycosyl prote in. The comparison of the must and the corresponding wine proteic frac tions isolated by concanavalin A shows that the two heterogeneous MW m olecules (24/25 and 60/64 kDa) originate from the grape berry. In addi tion, they suffer no modification during the alcoholic fermentation.