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DNA studies supported by matrix-assisted laser desorption ionization−time of flight mass spectrometry analysis of seed proteins showed that the Vitis viniferared grape variety Raboso Veronese is the progeny of a spontaneous cross between Raboso Piave (red) and Marzemina Bianca (white) varieties. In the present work, the main secondary grape metabolites of Raboso varieties were studied, and their enological potential was evaluated and compared with that of other red varieties reported in the literature. In general, Raboso grapes had high flavonoid contents and high percentages of polyphenols extractable in winemaking and substantial contents of norisoprenoid aroma precursors. Raboso Veronese stood out for its high content of cyanidin and had higher (+)-catechin and (−)-epicatechin contents than Raboso Piave and abundant quercetin glucoside, indicating substantial plant biosynthesis toward compounds dihydroxylated in the B-ring. Study of secondary grape metabolites is confirmed as an effective tool in differentiating similar varieties, in particular on the basis of polyphenol profiles.

In this microreview, the differences in the catalytic cycle of two copper/quinone-containing amine oxidases, one from lentil seedlings, representative of plant enzymes, and the other from bovine serum, typical of mammalian enzymes, are discussed. Although both enzymes are involved in the control of the levels of mono-, di-, and polyamines, and contain the same organic cofactor, the quinone of 2,4,5-trihydroxyphenylalanine, known as TOPA or TPQ, lentil amine oxidase operates in a different way and with a much higher catalytic activity than the bovine serum enzyme. The role of copper in the two enzymes is also discussed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Abstract: In this review the characteristics of the prosthetic group and the role of copper in amine oxidase purified from lentil seedlings are compared with the corresponding features of the amine oxidase isolated from bovine serum. Although both enzymes contain the same organic cofactor, the 6-hydroxydopa (2,4,5-trihydroxyphenethylamine) quinone, the catalytic cycle of lentil seedling amine oxidase operates through a Cu(I)-free-radical intermediate of the cofactor, whereas in bovine serum enzyme the radical form was not observed. The role of the metal in the catalytic mechanism of the two enzymes is also discussed. Moreover, the energetic domains and the effect of the temperature on activity, for both enzymes, are examined using differential scanning calorimetry.

Stilbenes are one of the main classes of grape polyphenols associated with the beneficial effects of drinking wine. In the present study, a “suspect screening” metabolomics approach was used to study these grape compounds. Analysis was performed by Ultra High Performance Liquid Chromatography/Quadrupole Time-Of-Flight (UHPLC/QTOF) mass spectrometry and compounds were identified using the database GrapeMetabolomics expressly constructed. By this approach, a total of 18 stilbene derivatives was identified in two V. vinifera red grape varieties (cvs. Raboso Piave and Primitivo) on the basis of accurate mass measurements and isotopic patterns. Identifications were confirmed by multiple mass spectrometry (MS/MS). Bioactive stilbenes such as trans-resveratrol, Z- and E-piceid, piceatannol and Z- and E-astringin, and several resveratrol dimers, trimers and tetramers such as pallidol and pallidol-3-O-glucoside, E- and Z--viniferin, E- and Z-δ-viniferin, caraphenol B, parthenocissin A, E- and Z-miyabenol C, hopheapenol, ampelopsin H, vaticanol C-like or isohopeaphenol, were identified. In our knowledge, some of these resveratrol trimers and tetramers were reported in grape for the first time.

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