%0 Journal Article %A Kalliopi A. Roubelakis-ANGELAKIS %A W. Mark Kliewer %T Phenylalanine Ammonia-Lyase in Berries of Vitis vinifera L.: Extraction and Possible Sources of Error During Assay %D 1985 %R 10.5344/ajev.1985.36.4.314 %J American Journal of Enology and Viticulture %P 314-315 %V 36 %N 4 %X Phenylalanine ammonia-lyase (PAL) activity in Vitis vinifera L. cv. Cardinal was present in the epidermal cell layers of the berries; however, extracts from acetone- or N-pulverized whole or peeled berries showed no activity. Extracts from N-pulverized skins showed greater enzyme activity than extracts from acetone-pulverized skins. Preparations of the enzyme by differential centrifugation of whole berries exhibited lower activities than analogous skin PAL extracts. Presence of polyvinyl polypyrrolidone (PVP) or polyethylene glycol (PEG) 4000 was indispensable for PAL activity in all the tested methods of enzyme extraction. Several factors during assay of PAL activity may cause alterations in the A290, such as the pH of the reaction mixture, the endogenous phenylalanine level, the duration of the reaction, and the composition of the reaction mixture; the average Km value for L-phenylalanine of Cardinal berry skin PAL was (2.3 ± 1.6) [unknown] 10-4M. %U https://www.ajevonline.org/content/ajev/36/4/314.full.pdf