The rates of oxidation of ent-kaur-16-ene to ent-kaur-16-en-19-oi, ent-kaur-16-en-19-al, ent-kaur-16-en-19-oic acid, and ent-kaur-16-en7a-ol-19-oic The diterpene hydrocarbon ent-kaur-16-ene2 is oxidized via a series of irreversible steps in the sequence kaurene3 to kaurenol

Three distinct potato (Solanum tuberosum) lipid acyl-hydrolases have been isolated and characterized. Nonfluorescent esters of the fluorescent alcohols, N-methylindoxyl and N-methylumbelliferone, have been used as convenient substrates for lipid acyl-hydrolase estimation. Enzyme I has been shown to be a neutral lipase which favors glyceryl triolein over the di-and monoolein, which shows no activity with phospho-and galactolipids and which favors long chain fatty acid esters of N-methylindoxyl over the butyrate ester. Enzyme II, while attacking glyceryl mono-and diolein, as well as favoring the butyrate ester of N-methylindoxyl over the myristate ester, is basically a phospholipid and galactolipid acylhydrolase. Enzyme III may reasonably be considered an esterase, since it hydrolyzes glyceryl monoolein exclusively among the neutral lipids, shows minimal activity on phospho-and galactolipids, and hydrolyzes N-methylindoxylbutyrate exclusively compared with N-methylindoxylmyristate.The respiration of freshly prepared potato tuber slices is qualitatively different from that of the intact tuber. While the respiratory substrate of intact tubers is carbohydrate, that of fresh slices is predominantly lipid (14). Lipid is sparse in potato tubers (8). For this reason, as well as because of the extensive disintegration of membrane ultrastructure observed in fresh slices of certain bulky plant storage organs (13), we have come to the view that the source of lipid substrate in fresh potato slices is primarily cell membranes.Lipid-degrading enzymes are prevalent in potato tuber. Galliard (8, 9) has demonstrated the rapidity with which lipids are hydrolyzed and peroxidized in potato homogenates, even at low temperature. In the context of our interests, we have discovered that as much as 20% of tissue lipid, primarily galacto-and phospholipids, is degraded in slices in several sec following cutting, while as much as 40% is lost in a matter of min (A. to the anomalous respiratory behavior of fresh slices. Insofar as fresh slice respiration comprises a significant component of fatty acid a-oxidation (16,22), there is further reason to acknowledge lipolytic acyl-hydrolase action as a primary event in the wake of slicing.In the course of time, lipid oxidation gives way to carbohydrate oxidation in potato slices (14). Our interest in potato lipases centers on the role they play in the determination of tissue respiratory behavior. Why does cutting initiate lipolytic activity? Why is lipid acyl-hydrolase activity suppressed with time in vivo in aging potato slices? Our studies indicated the presence of several lipid acyl-hydrolases in potato, in contrast to the single enzyme first reported by Galliard (8, 9; cf. 10, 11). The enzymes are characterized below, and a suggestion is made as to which enzyme corresponds to that described by Galliard. MATERIALS AND METHODS

The response of pea plants (Pisum sativum L.) to the presence of 192 mM NaCl or of 10-5 abscisic acid (ABA) was similar: shoot growth was inhibited, internal osmolarity and the content of organic solutes increased, and proline accumulated. It appears that most but not all of the new proline synthesized due to stress is located in the cytoplasmic compartment. The responses of the plant to salinity and externally applied ABA differed, apparently, in the mechanism of adjustment of the internal osmolarity: mainly ion absorption in the first, mainly synthesis of organic osmotica in the second. Potassium might have a special role in controlling internal events in pea shoots. Increase in the internal ABA content may serve as a trigger for the changes in pea shoots, but the sequence of events in pea roots may be different; the trigger may be some mechanism other than ABA accumulation. In this study ABA had no effect on root growth.

A potato (Solanum tuberosum) phospholipid acyl-hydrolase, whichin the pH range 7.5 to 8.5-is at least 10,000 times more effective with phospholipids than with galactolipids, has been purified and characterized. It is a soluble enzyme readily distinguished from a neutral lipid lipase and a third lipid acyl-hydrolase which, while acting on phospholipid, shows a decided preference for glyceryl monoolein. The phospholipase in question has a pH optimum of 8.5, is stimulated by Ca2l at pH above 7.5 and inhibited by Ca2l at lower pH, is not dependent on detergents although stimulated by Triton X-100 to a moderate extent, and remains very active at temperatures close to zero. The phospholipids of intact potato mitochondria are highly susceptible to degradation by potato phospholipase, and it is suggested that this enzyme is involved in the extensive lipid breakdown which occurs in fresh potato slices following cutting, and in the deterioration of mitochondria during their preparation and aging.In the preceding paper (14), we established the presence of three distinct lipid acyl-hydrolases in potato tuber with different specificities. Enzyme I was shown to be an acyl-hydrolase for neutral lipids. Enzyme II showed a preference for phospholipids and galactolipids. Enzyme III, while attacking phospholipids and galactolipids to some extent, displayed a pronounced specificity and activity towards glycerol monoolein. A generic lipolytic acyl-hydrolase from potato described by Galliard (8,9) and, more recently, shown to comprise several isoenzymes (1 1) seemingly encompasses our enzymes II and III. Disparities between our enzyme II and Galliard's enzyme with respect to phospholipid acyl-hydrolase activity, in particular, caused us to describe further the phospholipase characteristics of our enzyme II, and to compare it with Galliard's enzyme and with our enzyme III. Recently, a phospho-and galactolipase from potato has been isolated (15) which resembles our enzyme II.

ABSTRACTby Gunsalus et al. [7] for recent summaries of information about these and other systems.)Cyt P-450-dependent oxidases have also been reported in higher plant systems, but the characteristics of these have not been very thoroughly described. Murphy and West (22) (34), and from potato tubers (4). However, no function was ascribed to the P-450 from these sources. The characteristics of the transcinnamic acid 4-hydroxylase activity in microsomes of pea seedlings (28) and Jerusalem artichoke tubers (2) implicated Cyt P-450 in this oxidation. A recent paper by Potts et al. (27) provides definitive evidence for Cyt P450 participation in this 4-hydroxylation of trans-cinnamic acid by microsomes from sorghum seedlings and further describes a number of characteristics of the electron transfer reactions associated with the reaction. Finally, Madyastha et al. (17) and Meehan and Coscia (21) have shown a role for Cyt P-450 in the 10-hydroxylation of geraniol and nerol by vacuolar preparations from Vinca rosea seedlings.The preceding paper by Hasson and West (9) dealt with the pyridine nucleotide and flavin nucleotide cofactor requirements for the mixed function oxidation of kaurene4 and some of its oxidized derivatives (kaurenol, kaurenal, and kaurenoic acid) in microsomes from the endosperm of immature M. macrocarpus seed. This paper is concerned with the description of some of the electron transfer components found in these microsomal preparations and their possible involvement in these oxidase reactions.MATERIALS AND METHODS Microsomal Preparations. The microsomal fraction was prepared from a homogenate of endosperm of immature wild cu-2 See Figure 1 of Hasson and West (9) for the structure of this compound.3 Marah macrocarpus (Greene) Greene was earlier classified as Echinocystis macrocarpa Greene. The latter name has been used in earlier publications from our laboratory dealing with the biochemical properties of immature seed of this plant.