Purification and Characterization of an A Type Phospholipase from Potato and Its Effect on Potato Mitochondria

Abstract

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.

An octaethylene glycol monododecyl ether‐based mixed micellar assay for determining the lipid acyl hydrolase activity of patatin

“…Since patatin has been estimated to be 30-40% of the total soluble tuber protein, the maximum purification can only be 3-4 times that of the crude extract. Hasson et al (30) and Bohac (14) reported a 25-and 21-fold increase, respectively, in esterase specific activity; this greater increase in specific activity was attributed to the removal of an inhibitor or to a change in protein conformation. This paper also demonstrates the applicability of a procedure that uses the nonionic detergent C 12 E 8 for measuring patatin esterase activity.…”

Polyamines and wounded storage tissues – Inhibition of RNase activity and solute leakage

“…The increased RNase activity in response to mechanical damage and wounding is probably related to enzyme activation rather than to de novo synthesis (Kahl 1978). Sitnilarly, excision of beet root and potato storage tissue resulted first in extensive membrane degradation (Jackman and Van Steveninck 1967), which is reflected in the activity of several lipases (Galliard 1970, Hasson andLaties 1976). Increased synthesis and rearrangement of membrane components occur at later stages only, prior to the increase in mitotic activity (Benveniste 1978).…”

The liberation of free fatty acids in potato slices at low temperature

“…This fast liberation of FFA could be due to higher activity of the enzymes during the first part of the blanching bath. The activity of lipolytic acylhydrolase in potato tubers, particularly phospholipase, has been shown to increase with increasing temperature up to 50~ (7). Between 15~ and 25~ the activity increases most, especially in the presence of Ca 2+.…”