Phosphatidic Acid and Glyceride Synthesis by Particles from Spinach Leaves

Cheniae, George M.

doi:10.1104/pp.40.2.235

Cited by 44 publications

(10 citation statements)

References 32 publications

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“…However, EDTA at concentrations above mm inhibits the formation of PA in our system. This is in agreement with the findings of Cheniae (7). He showed that the formation of PA in spinach leaf preparations is not dependent on added Mg2b ut is inhibited by EDTA at a concentration of 10 mm, and that the formation of PA occurs over a broad pH range.…”

Section: Discussionsupporting

confidence: 81%

“…The enzymatic reaction in cucumber cotyledon homogenates that incorporates sn-glycerol-3-P into PA resembles that of spinach leaves (7,25) and avocado mesocarp (2) requirement for ATP and CoASH. Cheniae (7) has shown that the incorporation of sn-glycerol-3-P by spinach particles can be stimulated by the addition of free fatty acids (1.5-fold stimulation by 0.2 mm palmitic acid).…”

Section: Discussionmentioning

confidence: 99%

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Studies on Phospholipid-synthesizing Enzyme Activities during the Growth of Etiolated Cucumber Cotyledons

Macher

Brown²,

McManus³

et al. 1975

Plant Physiol.

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The enzymatic incorporation of stn-glycerol 3-phosphate into lipid by extracts of cucumber (Cucumis sativus) cotyledons showed an absolute requirement for ATP (saturation 2 mM). The incorporation was stimulated 4-fold by 0.2 mM oleate. Ethyldiaminetetraacetate stimulated the incorporation at concentrations below 1 mM and inhibited at higher concentrations. Mg2+ did not affect the reaction. Triton X-100 and Cutscum inhibited the reaction, while a third detergent, Span 80, was stimulatory. p-Mercuribenzoate was inhibitory. The enzymatic reaction has a pH optimum in the range of 8.8 to 9.6. The Michaelis constant was 112 ,uM for sn-glycerol 3-phosphate. The major amount of product was phosphatidic acid, the remainder was diacylglycerol, monoacylglycerol, and an unknown phospholipid. We have asked the second question in response to a suggestion put forward by Pieringer et al. (24) in a paper on PA synthesis in E. coli. They have shown that E. coli can synthesize PA by two separate reactions: (a) acylation of sn-glycerol 3-phosphate, and (b) phosphorylation of 1, 2-diacyl-sn-glycerol. The first reaction accounts for de novo synthesis. Pieringer et al. (24) have suggested that the second reaction acts as a scavenger system for glycerides formed from partially degraded phospholipids. Since bacteria must rapidly conform to changing environments (for example via membrane alterations), an enzyme system capable of utilizing partially degraded phospholipids for new phospholipid synthesis would be more efficient than a system using the products from fully degraded phospholipids. In the same manner, plants could benefit by phosphorylating partially degraded triacylglycerols to provide phospholipid precursors during germination. Bradbeer and Stumpf (6) have reported the diglyceride kinase activity in peanut cotyledons. MATERIALS AND METHODS

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Section: Discussionsupporting

confidence: 81%

Section: Discussionmentioning

confidence: 99%

Studies on Phospholipid-synthesizing Enzyme Activities during the Growth of Etiolated Cucumber Cotyledons

Macher

Brown²,

McManus³

et al. 1975

Plant Physiol.

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“…In plants very little published information exists on the overall pathways by which triglycerides arise, even less on the detailed enzymic steps. Labelled glycerol 3-phosphate is incorporated into phosphatidic acid by spinach-leaf microsomal fractions [2,3] and the label is subsequently incorporated either into more complex phospholipids [Z] or triglycerides [3]. The bcst evidence for the complete glycerol phosphate pathway in plants comes from the work of Barron and Stumpf [4] who showed that a microsomal fraction from avocado mesocarp incorporated glycerol phosAbbreviation.…”

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confidence: 99%

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Studies on Seed‐Oil Triglycerides

Gurr

Blades

Appleby

et al. 1974

European Journal of Biochemistry

101

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1. Crambe seeds harvested 6 -30 days after flowering actively incorporated radioactive precursors into lipids. The distribution of label among the different lipid classes depended on the precursor, the age of the seed, and the duration of the incubation.2. Labelled acetate was incorporated preferentially into phospholipids of whole seeds but the proportion of the radioactivity located in triglycerides increased as the age of the seed increased.3. Uniformly labelled glucose was incorporated readily into the glycerol moiety of glycerolipids but not a t all into the fatty acid moiety. The largest proportion was found in the phospholipid fraction and this proportion increased as the age of the seed increased, in contrast to labelled acetate.4. 1:nlformly labelled glycerol was actively incorporated into glycerolipids of whole seeds. Phospholipids were the first fraction to be labelled, and in this fraction labelled phosphatidic acid could be detected at early time periods. Subsequently, diglycerides became labelled and finally triglycerides. Labelled glycerol was quickly converted into a number of water-soluble metabolites, one of the most rapidly labelled of which was glycerol phosphate. Taken together these data are consistent with the presence of the glycerol phosphate pathway for triglyceride synthesis in maturing Crambe seeds.5. A fat fraction has been isolated from mature and maturing Crambe seeds by homogenisation of the seeds followed by flotation in the centrifugc. Electron microscopic examination indicated that the fraction contains the oil bodies that are the storage form of the oil in the seed in vivo.6. The isolated oil bodies contain 75O/, by weight of lipid and 190/, of protein. About 900/, of the lipid is triglyceride, the remainder is mostly phospholipid. No glycolipid is present. .The isolated fat fraction catalysed the conversion of different substrates, malonyl-CoA, long chain acyl-CoA and glycerol 3-phosphate into lipids. Evidence is presented that this is not due to contamination from other cell fractions.The pathways of biosynthesis of triglycerides are well worked out in animal tissues [l]. In plants very little published information exists on the overall pathways by which triglycerides arise, even less on the detailed enzymic steps. Labelled glycerol 3-phosphate is incorporated into phosphatidic acid by spinach-leaf microsomal fractions [2,3] ___-phate first into phosphatidic acid, then into diglycerides and finally into triglycerides, but no similar work has been done with seeds.In a previous paper we have described changes in oil composition as the Crambe seed matures and the complete stereospecific analysis of the seed-oil triglycerides [ 5 ] . Electron microscopy of thin sections of mature Crambe seeds, fixed and stained with osmium tetroxide, revealed cells packed with oil bodies with a mean diameter of about 1 pm. I n this paper we describe the isolation of the oil storage bodies, their chemical composition, and their enzymic activity and present evidence for the existence of the glyce...

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“…Among the phospholipids reportedly synthesized by plant mitochondria are phosphatidic acid (4,5,11,42), CDP-diglyceride (1,10,11,38,39), phosphatidylglycerol (10,12,26,30), cardiolipin (10,12), and phosphatidylethanolamine via the decarboxylation ofphosphatidylserine (27). In addition, there is evidence that plant mitochondria have the capacity to synthesize phosphatidylcholine via the methylation of phosphatidylethanolamine (31) as well as the phosphorylcholine-glyceride transferase reaction (9).…”

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Phospholipid Metabolism in Plant Mitochondria

Sparace¹,

Moore²

1979

Plant Physiol.

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Intact mitochondria from the endosperm of castor bean were isolated on linear sucrose gradients. These mitochondria were ruptured and the membranes separated on discontinuous sucrose gradients into outer membrane, intact inner membrane, and ruptured inner membrane fractions. Each membrane fraction was examined for its capacity to synthesize phosphatidyl4ycerol, CDP-diglyceride, phosphatidylcholine via methylation, and phosphatidic acid. The syntheses of phosphatidylglycerol, CDPdiglyceride, and phosphatidylcholine were localized exclusively in the inner mitochondrial membrane fractions while phosphatidic acid synthesis occurred in both the inner and outer mitochondrial membranes.

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Phosphatidic Acid and Glyceride Synthesis by Particles from Spinach Leaves

Cited by 44 publications

References 32 publications

Studies on Phospholipid-synthesizing Enzyme Activities during the Growth of Etiolated Cucumber Cotyledons

Studies on Phospholipid-synthesizing Enzyme Activities during the Growth of Etiolated Cucumber Cotyledons

Studies on Seed‐Oil Triglycerides

Phospholipid Metabolism in Plant Mitochondria

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