Fat metabolism in higher plants. Beta-hydroxylation of fatty acids by a soluble preparation from maturing avocado mesocarp.
Ontology highlight
ABSTRACT:
SUBMITTER: Harwood JL
PROVIDER: S-EPMC1174551 | biostudies-other | 1972 Dec
REPOSITORIES: biostudies-other
Similar Datasets
Project description:1. Plastid and mitochondrial preparations were obtained by density-gradient centrifugation of homogenates made by gentle disintergration of avocado fruit mesocarp and cauliflower bud tissue. 2. The mitochondrial preparations had respiratory activity but did not incorporate [1-14C]acetate into fatty acids. 3. The plastid preparations incorporated [1--14C]acetate into the range of fatty acids found in the parent tissue. No fatty acid synthetase activity could be detected in the 12000g supernatant of these homogenates. 4. Homogenates produced by rupture of the tissue in an Ato-Mix blender and plastid preparations disintegrated by ultrasonic treatment both had fatty acid synthetase activity which did not sediment at 105000g and which formed mainly [14-C]stearate from [2-14C]malonyl-CoA. 5. It is concluded that the plastids are the principal site of fatty acid biosynthesis in the tissues studied.
| S-EPMC1165321 | biostudies-other
Project description:Chilling injury (CI) symptoms in avocado (Persea americana Mill.) fruit, expressed as mesocarp discoloration, were found to be associated with embryo growth and ethylene production during cold storage. In cvs Ettinger and Arad most mesocarp discoloration was located close to the base of the seed and was induced by ethylene treatment in seeded avocado fruit. However, ethylene did not increase mesocarp discoloration in seedless fruit stored at 5 degrees C. Application of ethylene to whole fruit induced embryo development inside the seed. It also induced seedling elongation when seeds were imbibed separately. Persea americana ethylene receptor (PaETR) gene expression and polyphenol oxidase activity were highest close to the base of the seed and decreased gradually toward the blossom end. By contrast, expressions of PaETR transcript and polyphenol oxidase activity in seedless avocado fruit were similar throughout the pulp at the base of the fruit. Application of the ethylene inhibitor, 1-methylcyclopropene, decreased mesocarp browning, embryo development, seedling growth, and ion leakage, and down-regulated polyphenol oxidase activity. The results demonstrate that ethylene-mediated embryo growth in whole fruit is involved in the mesocarp response to ethylene perception and the development of CI disorders.
| S-EPMC2652053 | biostudies-literature
Project description:The NADPH-linked 3-oxoacyl-(acyl-carrier protein) (ACP) reductase (EC 1.1.1.100), also known as 'beta-ketoacyl-ACP reductase', has been purified from the mesocarp of mature avocado pears (Persea americana). The enzyme is inactivated by low ionic strength and low temperature. On SDS/PAGE under reducing conditions, purified 3-oxoacyl-ACP reductase migrated as a single polypeptide giving a molecular mass of 28 kDa. Gel-filtration chromatography gave an apparent native molecular mass of 130 kDa, suggesting that the enzyme is tetrameric. The enzyme is inactivated by dilution, but some protection is afforded by the presence of NADPH. Kinetic constants have been determined using synthetic analogues as well as the natural ACP substrate. It exhibits a broad pH optimum around neutrality. Phenylglyoxal inactivates the enzyme, and partial protection is given by 1 mM-NADPH. Antibodies have been raised against the protein, which were used to localize it using immunogold electron microscopy. It is localized in plastids. N-Terminal amino-acid-sequence analysis was performed on the enzyme, and it shows close structural similarity with cytochrome f. Internal amino-acid-sequence data, derived from tryptic peptides, shows similarity with the putative gene products encoded by the nodG gene from the nitrogen-fixing bacterium Rhizobium meliloti and the gra III act III genes from Streptomyces spp.
| S-EPMC1149621 | biostudies-other
Project description:1. The range of fatty acids formed by preparations of ultrasonically ruptured avocado mesocarp plastids was dependent on the substrate. Whereas [1-14C]palmitate and [14C]oleate were the major products obtained from [-14C]acetate and [1-14C]acetyl-CoA, the principal product from [2-14C]malonyl-CoA was [14-C]stearate. 2. Ultracentrifugation of the ruptured plastids at 105000g gave a supernatant that formed mainly stearate from [2-14C]malonyl-CoA and to a lesser extent from [1-14C]acetate. The incorporation of [1-14C]acetate into stearate by this fraction was inhibited by avidin. 3. The 105000g precipitate of the disrupted plastids incorporated [1-14C]acetate into a mixture of fatty acids that contained largely [14C]plamitate and [14C]oleate. The formation of [14C]palmitate and [14C]oleate by disrupted plastids was unaffected by avidin. 4. The soluble fatty acid synthetase was precipitated from the 105000g supernatant in the 35-65%-saturated-(NH4)2SO4 fraction and showed an absolute requirement for acyl-carrier protein. 5. Both fractions synthesized fatty acids de novo.
| S-EPMC1165322 | biostudies-other
Project description:BackgroundAvocado fruit contains aliphatic acetogenins (oft-acetylated, odd-chain fatty alcohols) with promising bioactivities for both medical and food industries. However, we have scarce knowledge about their metabolism. The present work aimed to study changes in acetogenin profiles from mesocarp, lipid-containing idioblasts, and seeds from 'Hass' cultivar during fruit development, germination, and three harvesting years. An untargeted LC-MS based lipidomic analysis was also conducted to profile the lipidome of avocado fruit in each tissue.ResultsThe targeted analysis showed that acetogenin profiles and contents remained unchanged in avocado mesocarp during maturation and postharvest ripening, germination, and different harvesting years. However, a shift in the acetogenin profile distribution, accompanied with a sharp increase in concentration, was observed in seed during early maturation. Untargeted lipidomics showed that this shift was accompanied with remodeling of glycerolipids: TAGs and DAGs decreased during fruit growing in seed. Remarkably, the majority of the lipidome in mature seed was composed by acetogenins; we suggest that this tissue is able to synthesize them independently from mesocarp. On the other hand, lipid-containing idioblasts accumulated almost the entire acetogenin pool measured in the whole mesocarp, while only having 4% of the total fatty acids. The lipidome of this cell type changed the most when the fruit was ripening after harvesting, TAGs decreased while odd-chain DAGs increased. Notably, idioblast lipidome was more diverse than that from mesocarp.ConclusionsEvidence shown here suggests that idioblasts are the main site of acetogenin biosynthesis in avocado mesocarp. This work unveiled the prevalence of aliphatic acetogenins in the avocado fruit lipidome and evidenced TAGs as initial donors of the acetogenin backbones in its biosynthesis. It also sets evidence for acetogenins being included in future works aimed at characterizing the avocado seed, as they are a main component of their lipidome.
| S-EPMC5623960 | biostudies-literature
Project description:Herein, we report the first decarboxylative hydroxylation to synthesize phenols from benzoic acids at 35 °C via photoinduced ligand-to-metal charge transfer (LMCT)-enabled radical decarboxylative carbometalation. The aromatic decarboxylative hydroxylation is synthetically promising due to its mild conditions, broad substrate scope, and late-stage applications.
| S-EPMC8596882 | biostudies-literature
Project description:Avocado (Persea americana Mill.) is an economically important crop because of its high nutritional value. However, the absence of a sequenced avocado reference genome has hindered investigations of secondary metabolism. For next-generation high-throughput transcriptome sequencing, we obtained 365,615,152 and 348,623,402 clean reads as well as 109.13 and 104.10 Gb of sequencing data for avocado mesocarp and seed, respectively, during five developmental stages. High-quality reads were assembled into 100,837 unigenes with an average length of 847.40 bp (N50 = 1725 bp). Additionally, 16,903 differentially expressed genes (DEGs) were detected, 17 of which were related to carotenoid biosynthesis. The expression levels of most of these 17 DEGs were higher in the mesocarp than in the seed during five developmental stages. In this study, the avocado mesocarp and seed transcriptome were also sequenced using single-molecule long-read sequencing to acquired 25.79 and 17.67 Gb clean data, respectively. We identified 233,014 and 238,219 consensus isoforms in avocado mesocarp and seed, respectively. Furthermore, 104 and 59 isoforms were found to correspond to the putative 11 carotenoid biosynthetic-related genes in the avocado mesocarp and seed, respectively. The isoform numbers of 10 out of the putative 11 genes involved in the carotenoid biosynthetic pathway were higher in the mesocarp than those in the seed. Besides, alpha- and beta-carotene contents in the avocado mesocarp and seed during five developmental stages were also measured, and they were higher in the mesocarp than in the seed, which validated the results of transcriptome profiling. Gene expression changes and the associated variations in gene dosage could influence carotenoid biosynthesis. These results will help to further elucidate carotenoid biosynthesis in avocado.
| S-EPMC6747375 | biostudies-literature
Project description:The first and key step in alkane metabolism is the terminal hydroxylation of alkanes to 1-alkanols, a reaction catalyzed by a family of integral-membrane diiron enzymes related to Pseudomonas putida GPo1 AlkB, by a diverse group of methane, propane, and butane monooxygenases and by some membrane-bound cytochrome P450s. Recently, a family of cytoplasmic P450 enzymes was identified in prokaryotes that allow their host to grow on aliphatic alkanes. One member of this family, CYP153A6 from Mycobacterium sp. HXN-1500, hydroxylates medium-chain-length alkanes (C6 to C11) to 1-alkanols with a maximal turnover number of 70 min(-1) and has a regiospecificity of > or =95% for the terminal carbon atom position. Spectroscopic binding studies showed that C6-to-C11 aliphatic alkanes bind in the active site with Kd values varying from approximately 20 nM to 3.7 microM. Longer alkanes bind more strongly than shorter alkanes, while the introduction of sterically hindering groups reduces the affinity. This suggests that the substrate-binding pocket is shaped such that linear alkanes are preferred. Electron paramagnetic resonance spectroscopy in the presence of the substrate showed the formation of an enzyme-substrate complex, which confirmed the binding of substrates observed in optical titrations. To rationalize the experimental observations on a molecular scale, homology modeling of CYP153A6 and docking of substrates were used to provide the first insight into structural features required for terminal alkane hydroxylation.
| S-EPMC1539980 | biostudies-literature
Project description:The present study evaluated the performance of some enzymatic and non-enzymatic antioxidant systems against oxidative stress for 10 to 30 d of refrigeration (R) and 15 to 50 d in controlled atmosphere (CA) conditions in both exocarp and mesocarp of Hass avocados from early and late harvests and at shelf life (SL) or consumption maturity. The possible relationship of the antioxidant systems with the occurrence of physiological disorders is also evaluated. The results indicate that the enzymatic system-superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), phenylalanine ammonium lyase (PAL) and polyphenoloxidase (PPO)-as well as the non-enzymatic system-such as phenolic compounds (PC)-showed different responses to the stress generated during storage and shelf life. In general, SOD, CAT, PAL and PPO did not significantly vary in storage (R or CA). At consumption maturity, SOD, POD and PAL activities decreased in the mesocarp (RSL and CASL), while CAT increased in the exocarp for CASL15-50d. PC instead decreased in the exocarp as the harvest period progressed while it increased in the mesocarp. Physiological disorders (dark spots) showed only in refrigeration on the exocarp at R30d and in mesocarp at RSL30d coincident with low SOD and low SOD and POD activity values, as well as low PC contents (p-coumaric and its derivatives and caffeic acid derivatives), respectively. The results support the use of CA as a postharvest technology to prevent the development of physiological disorders through the joint action of antioxidative defenses during avocado transport to distant markets until consumption maturity is reached.
| S-EPMC10707783 | biostudies-literature
Project description:1. The lower regions of the stem of celery (Apium graveolens L.) contain a soluble enzyme that hydrolyses phosphatidylinositol. 2. The lipoidal product of hydrolysis is diacylglycerol, and the water-soluble products are 1:2-cyclic phosphoinositol and phosphoinositol in the approximate proportions of 60% and 40% respectively: this indicates that a phosphodiesterase (phospholipase C-like) activity is cleaving the phosphatidylinositol. 3. The enzyme requires a bivalent cation, Ca2+ being the most effective activator. 4. The enzyme has a pH optimum, depending on conditions of assay, of pH 5.9-6.6 and in this pH range shows no detectable activity against phosphatidylcholine or phosphatidylethanolamine. 5. The activity is stimulated by phosphatidic acid and slightly inhibited (30% at concentrations equimolar with phosphatidylinositol) by phosphatidylcholine. 6. The phosphodiesterase was also detected (but not quantified) in the tips of the flowers in cauliflowers, in outer leaves of onion and in the elongating stem of daffodils. 7. The enzyme's properties are compared with equivalent mammalian enzymes, and its possible role in the catabolism of phosphatidylinositol in higher plants is discussed.
| S-EPMC1162332 | biostudies-other