EXTRACTION OF GRAPE BERRIES (VITIS-VINIFERA L) MITOCHONDRIA

Grapes berries (Vitis vinifera) mitochondria have been extracted and purified for the first time. A high polyvinylpyrrolidone concentration was used in order to avoid protein tannin binding and a pH adjustment was necessary to neutralize the vacuolar soap acidity. The main novelty of the protocol developed was the use of high osmoticum concentrations to avoid breakage of mitochondrial membranes. Oxidation rates similar to those obtained with other plant materials were obtained with Percoll gradient purification. Oxaloacetate triggered off a strong inhibition of succinate and malate oxidation and was excreted from the matrix against a concentration gradient. Comparison of the grape mitochondrial properties studied in vitro to the respiratory characteristics of the whole fruit suggested that mitochondria should be in partial anoxic conditions in situ when the fruit is at ripening stage.