Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Extraction and study of enzymes linked to malate metabolism in tree leaves. | 811s Ann. Sei. For. 1989 46 suppl. 811s-814s Forest Tree Physiology E. Dreyer et al. eds. Elsevier INRA Extraction and study of enzymes linked to malate metabolism in tree leaves D. Gerant A. Citerne c. Fabert and p. Dizengremel Laboratoire de Physìologie Végétale et Forestiere Université de Nancy I BP 239 54506 Vandoeuvre France Introduction It is well established that malate plays a central role in plant cellular metabolism Lance and Rustin 1984 . Malate is the organic acid which can be accumulated to the highest level in plant cells and its internal concentration can display normal daily fluctuations and can also present permanent or long-term changes with environmental conditions Lance and Rustin 1984 . Enzymes implicated in synthesis and catabolism of this substrate are widely distributed in the cellular compartments. If these enzymes have become well known in herbaceous plants Macrae 1971 Davis and Patil 1975 Wiskich and Dry 1985 Artus and Edwards 1985 very few studies have been made on woody plants Rite and Cheliak 1985 1986 Weimar and Rothe 1987 . In this study the extraction of enzymes linked to malate metabolism particularly those located in mitochondria was investigated in coniferous and deciduous leaves. Particular attention was devoted to the variations in enzyme capacities during the growing season. Finally the first steps of purification of these enzymes are presented and discussed. Materials and Methods Oak leaves Quercus pedonculata were collected in a local forest and spruce needles Picea abies in Donon Vosges mountains Twigs were cut and kept at 4 c until use. Based on previous studies the extraction buffer was sufficiently protective against deleterious compounds such as phenolic compounds tannins and terpenoids Gerant et al. 1988 . Fresh tissues were homogenized in a potter grinder at 4 c in the presence of the extraction buffer and centrifuged at 50 000 X g for 30 min. The supernatant was collected and desalted on a Sephadex G-25 column .
