Lipolytic Acyl Hydrolase Activity Research Articles

A novel patatin-like gene stimulated by drought stress encodes a galactolipid acyl hydrolase

A cDNA ( Vupat1) encoding a predicted 43 kDa protein was isolated from drought-stressed cowpea ( Vigna unguiculata) leaves. It has homology with patatin, a potato tuber storage protein with lipolytic acyl hydrolase activity. The recombinant protein VUPAT1 expressed in the baculovirus system displays preferentially galactolipid acyl hydrolase activity. Phospholipids are very slowly hydrolyzed and apparently triacylglycerols are not deacylated. Vupat1 promoter contains putative drought-inducible sequences. Northern blots showed that gene expression is stimulated by drought stress and is more pronounced in a drought-sensitive cultivar than in a drought-tolerant one. An involvement in drought-induced galactolipid degradation is proposed for VUPAT1.

A patatin-like protein with galactolipase activity is induced by drought stress in Vigna unguiculata leaves

This paper reports the cloning of a cDNA (Vupat 1) expressed in Vigna unguiculata leaves coding for a protein with 48% sequence homology to patatin, the major protein from potato tuber which has lipolytic acylhydrolase activity. Two cultivars differing in drought tolerance were ex-amined in Northern-blot analyses. Expression of Vupat 1 is stimulated by drought stress, especially in the drought-sensitive cultivar. Vupat 1 was expressed in the baculovirus system as a fusion protein secreted in the culture medium. The recombinant protein displays lipolytic activity towards monogalactosyldiacylglycerol, digalactosyldiacylglycerol and sulphoquinovosyldiacylglycerols.

A patatin-like protein with galactolipase activity is induced by drought stress in Vigna unguiculata leaves

This paper reports the cloning of a cDNA (Vupat1) expressed in Vigna unguiculata leaves coding for a protein with 48% sequence homology to patatin, the major protein from potato tuber which has lipolytic acylhydrolase activity. Two cultivars differing in drought tolerance were examined in Northern-blot analyses. Expression of Vupat1 is stimulated by drought stress, especially in the drought-sensitive cultivar. Vupat1 was expressed in the baculovirus system as a fusion protein secreted in the culture medium. The recombinant protein displays lipolytic activity towards monogalactosyldiacylglycerol, digalactosyldiacylglycerol and sulphoquinovosyldiacylglycerols.

A Thio-based Phospholipase Assay Employed for the Study of Lipolytic Acyl Hydrolase in the Ephemeral Corolla of Ipomoea tricolor

Summary A thioester-analogue of phosphatidylcholine was employed for the kinetic measurement of phospholipase activity in enzyme preparations from the corolla of Ipomoea tricolor. The corresponding lipolytic acyl hydrolase activity is constitutively high; its potential is sufficient for the almost instantaneous deacylation of all phospholipds in the tissue and, indeed, upon the homogenization of corolla tissue phospholipids are degraded rapidly. In the living cells, the enzyme seems to be functionally latent, probably because it is located in the vacuoles. Partial purifications comprising ammonium sulphate precipitation and chromatograhies (anion exchange, gel permeation and chromatofocussing) yielded preparations suitable for the characterization of lipolytic acyl hydrolase with regard to pH-optima (pH 5.5–6 and pH 8), size (70 and 120 kDalton) and isolelectric point (pH 4.3). The activity is inhibited by Ca-ions. The lipolytic acyl hydrolase of I. tricolor is considered to be part of the latent vacuolar lyric potential, which upon the collapse of subcellular compartmentation is responsible for the rapid degradation of residual cell constituents.

Developmental Change in C6-Aldehyde Formation by Soybean Leaves

Damage to plant leaves by wounding or freezing induces the production of large amounts of C(6)-compounds. However, the control of formation of these compounds in leaves is not yet clear. In the current study, C(6)-aldehyde formation by freeze-injured soybean leaves of different ages (based on the leaf positions on the plant) at stage R1 of plant development was investigated. The results demonstrate that C(6)-aldehyde formation by the soybean (Glycine max L.) leaves changes as leaves develop. Younger leaves produce high levels of C(6)-aldehydes, mainly composed of hexanal. Subsequently, as the leaves develop, the level of C(6)-aldehyde formation decreases markedly, followed by an increase with a large shift from hexanal to hexenals. Lipoxygenase and lipolytic acyl hydrolase activity was reduced, and, in contrast, hydroperoxide lyase activity increased. There was little difference in lipoxygenase substrate specificity for linoleic acid and linolenic acid, but hydroperoxide lyase preferentially utilized 13-hydroperoxy-9,11,15-octadecatrienoic acid. In the in vivo lipoxygenase substrate pool, the linoleic acid level declined and the relative level of linolenic acid increased. The change in ratios of linolenic acid to linoleic acid showed a similar trend during soybean leaf development to that of hexenals to hexanal.

Biochemical aspects of wound healing in yams (Dioscorea spp)

AbstractThe effects of wounding on the activities of certain enzymes and on the concentrations of selected metabolites were investigated in the tubers of white yam (Dioscorea rotundata). Lipolytic acyl hydrolase activity decreased and disappeared after 4 days whereas the activity of lipoxygenase, peroxidase and polyphenol oxidase increased to a maximum after 1, 4 and 5 days, respectively. The activities of lipoxygenase and polyphenol oxidase were much higher in the proximal half of the tubers than in the distal portion. The increase in lipoxygenase activity at the wound site was a localised phenomenon. The application of the antibiotic, tetracycline, during the early stages of wound healing substantially reduced the increase in the activities of polyphenol oxidase and lipoxygenase. The concentration of free amino acids, total polyphenols and ascorbate increased in response to wounding. Free amino acids steadily declined after 24 h following wounding.

Autolysis of membrane lipids in potato leaf homogenates: Effects of calmodulin and calmodulin antagonists

Potato leaves contain high levels of lipolytic acyl hydrolase activity which degrades phospholipids and galactolipids during homogenization and organelle isolation. Four calmodulin antagonists (dibucaine, tetracaine, trifluoperazine a and chlorpromazine) were found to inhibit the rate of hydrolysis of endogenous membrane lipids in homogenates of potato leaves. In contrast, the addition of calcium and purified calmodulin stimulated the rate of hydrolysis. These results indicate that a lipolytic acyl hydrolase activity in potato leaves appears to be mediated either directly or indirectly by calcium and calmodulin.

Inhibition of potato tuber lipoxygenase and lipolytic acyl hydrolase activities by nupercaine

The local anaesthetic, nupercaine, acts as an inhibitor of potato tuber lipoxygenase (LOX), when the incubation mixture also contains Triton X-100. The inhibition appears to be due to a change in the physical structure of the lipid substrate induced by nupercaine, rather than a direct effect on the enzyme. The assay of potato tuber lipolytic acyl hydrolase (LAH) by a coupled reaction involving LOX does not give an accurate estimation of lipolytic acyl hydrolase activity and the inhibition by nupercaine, of such an assay, is due to the inhibition of lipoxygenase activity by the combined presence of nupercaine and Triton.

Lipoxygenase‐ mediated cleavage of fatty acids in plant mitochondria

Incubation of cauliflower bud mitochondria in the presence of 5 mM CaCl2 results in a rapid hydrolysis of the main membrane phospholipsds. Under the action of phospholipase D, phosphatidic acid is produced and forms, within the membranes, a very labile complex with Ca2+ and HPO42‐ions present in the incubation medium. With time, one observes a first step characterized by the formation of phosphatidic acid, followed by a second step linked to the breakdown of this phospholipid. The enzyme responsible for the disappearance of phosphalidic acid has been identified as lipoxygenase. In the presence of molecular oxygen, this enzyme acts on the polyun‐saturated fatty acids of phosphatidic add (mainly C18:2 and C18:3) yielding small water‐soluble molecules, one of them being identified as malondialdehyde (1, 3‐propanedial). Experiments involving inhibitory conditions of the breakdown of phosphatidic acid indicate that lipoxygenase acts directly on membrane‐bound phosphatidic acid without previous, involvement of a lipolytic acyl hydrolase activity. In addition, the lipoxygenase activity is fully sensitive to hydroxamate derivatives. It is proposed that the lipoxygenase activity may account for a part of the mitochondrial alternative electron pathway that is insensitive to cyanide.

Calcium-dependent lipolytic acyl-hydrolase activity in purified plant mitochondria

Ageing of isolated potato mitochondria induced by CaCl 2 resulted in rapid enzymatic hydrolysis of the membrane phospholipids with the liberation of free fatty acids. The enzyme responsible for this effect was identified as. a membrane bound lipolytic acyl-hydrolase which was unmasked by CaCl 2. The presence of this lipolytic acyl-hydrolase induced severe functional impairments in the mitochondrial oxidative and phosphorylative properties.

Substrate specificity of potato lipoxygenase

The substrate specificity of potato lipoxygenase was examined using a partially purified enzyme preparation from tubers of a potato variety with low lipolytic acyl hydrolase activity. Potato lipoxygenase is fully active only on free linoleic acid or linolenic acid, and only acts directly on more complex glyceride moieties in the absence of any significant endogenous lipolytic acyl hydrolase activity.

Isoenzymes of lipolytic acyl hydrolase and esterase in potato tuber

Five varieties of potato ( Solanum tuberosum) were shown by gel- and free-flow-electrophoresis to exhibit multiple forms of lipolytic acyl hydrolase (LAH) and esterase enzymes. The electrophoretic patterns of LAH and esterase activities and protein differed with the variety and were characteristic for a given variety. In the variety (Golden Wonder) with the highest LAH activity ( p-nitrophenylpalmitate as substrate), this was 200-fold greater than the esterase activity ( p-nitrophenylacetate as substrate) and isoenzyme patterns for both enzymes were the most complex. In the variety with a very low LAH activity (Désirée), the LAH and esterase activities were similar and more simple isoenzyme patterns for these enzymes were observed.

米貯蔵時における脂質成分ならびに脂質加水分解酵素活性の変化

米貯蔵時における脂質成分ならびに脂質加水分解酵素活性の変化

An Improved Method for Determining Lipolytic Acyl-hydrolase Activity

An Improved Method for Determining Lipolytic Acyl-hydrolase Activity

An Improved Method for Determining Lipolytic Acyl-hydrolase Activity

An Improved Method for Determining Lipolytic Acyl-hydrolase Activity