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Characterization of a Grape Class IV Chitinase

Vincenzi, Simone, Bierma, Jan, Wickramasekara, Samanthi I., Curioni, Andrea, Gazzola, Diana, Bakalinsky, Alan T.
Journal of agricultural and food chemistry 2014 v.62 no.24 pp. 5660-5668
N-acetylglucosamine, Vitis vinifera, cell walls, chitin, chitinase, grape juice, grapes, growth retardation, pH, peptides, proteomics, temperature, wine yeasts
A chitinase was purified from Vitis vinifera Manzoni Bianco grape juice and characterized. On the basis of proteomic analysis of tryptic peptides, a significant match identified the enzyme as a type IV grape chitinase previously found in juices of other V. vinifera varieties. The optimal pH and temperature for activity toward colloidal chitin were found to be 6 and 30 °C, respectively. The enzyme was found to hydrolyze chitin and oligomers of N-acetylglucosamine, generating N,N′-diacetylchitobiose and N-acetylglucosamine as products, but was inactive toward N,N′-diacetylchitobiose. The enzyme exhibited both endo- and exochitinase activities. Because yeast contains a small amount of chitin in the cell wall, the possibility of growth inhibition was tested. At a concentration and pH expected in ripe grapes, no inhibition of wine yeast growth by the chitinase was observed.