Monogalactosyl Diglyceride Research Articles

Analysis of lipid composition of cell-bound membrane vesicles (CBMVs) derived from endothelial cells

Cell-bound membrane vesicles (CBMVs), a novel type of membrane vesicles, have been identified through a series of characterization tools. However, the lipid composition of CBMVs has not yet been characterized. This study focuses on the differences in lipid composition between CBMVs and cell membranes. In order to determine the lipid composition of CBMVs and cell membranes of Human umbilical vein endothelial cells (HUVECs) and find out differential metabolites, this study was carried out by isolating CBMVs lipids and characterizing them using high-performance liquid chromatography tandem secondary mass spectrometry (LC-MS/MS). The results showed the presence of 213 up-regulated and 726 down-regulated lipids in CBMVs compared to cell membranes which produced CBMVs. There are lipids expressed in CBMVs and not in cell membranes: DGDG 18:0_8:0, DGDG O-8:0_16:1, DGDG O-26:7_26:7, DGDG O-16:3_26:7, TG 15:4_21:5_22:5; 4O, PC 49:11, PG 19:5_38:10, PI 60:14, PI 44:9, PI 25:2, PI 43:5, PI 50:10, PS 55:10. DGDG (digalactosyl diglyceride), MGDG (monogalactosyl diglyceride) belongs to galactosyl diglyceride, promotes fat catabolism, which also has antioxidant and anti-inflammatory effects, and unsaturated diacylglycerols are a class of antioxidant compounds, which enables CBMVs to have a therapeutic potential.

Exogenous melatonin delays yellowing in harvested broccoli by maintaining chloroplast integrity

Yellowing of broccoli is a crucial limiting factor for its commercial value and consumer acceptance during postharvest. In this study, the impacts of exogenous melatonin (MEL) on chlorophyll content and fluorescence, as well as ultrastructure and membrane lipid metabolism of chloroplasts in broccoli were investigated during postharvest. The results showed that MEL treatment (200 μmol L−1) maintained the chlorophyll content, chloroplast autofluorescence and integral structure, and reduced the level ofserotonin in the chloroplasts in broccoli. Also, MEL treatment inhibited the membrane lipid peroxidation of chloroplasts, as indicated by low levels of superoxide anion (O2-), hydrogen peroxide (H2O2) and malondialdehyde (MDA), and high levels of endogenous MEL. In addition, the stability and fluidity of chloroplast membranes were also better maintained in the treated broccoli via increasing the contents of phosphatidylglyceroland (PG), monogalactosyldiglyceride (MGDG), digalactosyldiglyceride (DGDG) and unsaturated fatty acids as well as decreasing saturated fatty acid content and the activities of lipoxygenase (LOX) and lipase (LPS). Thus, the application of MEL facilitated the maintenance of chloroplast integrity, thus contributing to yellowing postponement and the extension of the storage life of broccoli.

Cerebral Gray and White Matter Monogalactosyl Diglyceride Levels Rise with the Progression of Alzheimer's Disease.

Multiple studies have reported brain lipidomic abnormalities in Alzheimer's disease (AD) that affect glycerophospholipids, sphingolipids, and fatty acids. However, there is no consensus regarding the nature of these abnormalities, and it is unclear if they relate to disease progression. Monogalactosyl diglycerides (MGDGs) are a class of lipids which have been recently detected in the human brain. We sought to measure their levels in postmortem human brain and determine if these levels correlate with the progression of the AD-related traits. We measured MGDGs by ultrahigh performance liquid chromatography tandem mass spectrometry in postmortem dorsolateral prefrontal cortex gray matter and subcortical corona radiata white matter samples derived from three cohorts of participants: the Framingham Heart Study, the Boston University Alzheimer's Disease Research Center, and the Arizona Study of Aging and Neurodegenerative Disorders/Brain and Body Donation Program (total n = 288). We detected 40 molecular species of MGDGs (including diacyl and alkyl/acyl compounds) and found that the levels of 29 of them, as well as total MGDG levels, are positively associated with AD-related traits including pathologically confirmed AD diagnosis, clinical dementia rating, Braak and Braak stage, neuritic plaque score, phospho-Tau AT8 immunostaining density, levels of phospho-Tau396 and levels of Aβ40. Increased MGDG levels were present in both gray and white matter, indicating that they are widespread and likely associated with myelin-producing oligodendrocytes-the principal cell type of white matter. Our data implicate the MGDG metabolic defect as a central correlate of clinical and pathological progression in AD.

Lipid/water interface of galactolipid bilayers in different lyotropic liquid-crystalline phases.

In this study, carried out using computational methods, the organisation of the lipid/water interface of bilayers composed of galactolipids with both α-linolenoyl acyl chains is analysed and compared in three different lyotropic liquid-crystalline phases. These systems include the monogalactosyldiglyceride (MGDG) and digalactosyldiglyceride (DGDG) bilayers in the lamellar phase, the MGDG double bilayer during stalk phase formation and the inverse hexagonal MGDG phase. For each system, lipid-water and direct and water-mediated lipid-lipid interactions between the lipids of one bilayer leaflet and those of two apposing leaflets at the onset of new phase (stalk) formation, are identified. A network of interactions between DGDG molecules and its topological properties are derived and compared to those for the MGDG bilayer.

Genetic variation in wheat grain quality is associated with differences in the galactolipid content of flour and the gas bubble properties of dough liquor

Lipids affect the quality of wheat flour for breadmaking. One possible mechanism is stabilization of the gas cells which are formed during dough mixing and expanded during fermentation, leading to a greater loaf volume and evenness of texture. We therefore compared the lipidomic profiles of flour and dough liquor fractions (which contain surface-active components present at the gas bubble interface) from two sets of wheat lines differing in allelic variation at a QTL for loaf volume. Analyses of fractions from three field trials showed consistent increases in the contents of galactolipids (monogalactosyl diglyceride and digalactosyl diglyceride) in flour and dough liquor of the lines with the increasing (good quality) allele. Biophysical analysis showed that this was associated with greater elasticity of the dough liquor fraction. This is consistent with published studies reporting a relationship between galactolipids and breadmaking quality and suggests a mechanism of action for the QTL.

The Serine Carboxypeptidase-Like Gene SCPL41 Negatively Regulates Membrane Lipid Metabolism in Arabidopsis thaliana.

The Arabidopsis has 51 proteins annotated as serine carboxypeptidase-like (SCPL) enzymes. Although biochemical and cellular characterization indicates SCPLs involved in protein turnover or processing, little is known about their roles in plant metabolism. In this study, we identified an Arabidopsis mutant, bis4 (1-butanol insensitive 4), that was insensitive to the inhibitory effect of 1-butanol on seed germination. We cloned the gene that was defective in bis4 and found that it encoded an SCPL41 protein. Transgenic Arabidopsis plants constitutively expressing SCPL41 were generated, oil body staining and lipidomic assays indicated that SCPL41-overexpressing plants showed a decrease in membrane lipid content, especially digalactosyl diglyceride (DGDG) and monogalactosyl diglyceride (MGDG) contents, while the loss of SCPL41 increased the membrane lipid levels compared with those in wild-type plants. These findings suggested that SCPL41 had acquired novel functions in membrane lipid metabolism.

Lipid Class and Fatty Acid Compositions of Dried Sea Cucumber Apostichopus japonicus

Introduction: Sea cucumber, Apostichopus japonicus, is becoming popular around the world due to its nutritional and medicinal properties. There are still no detailed chemical studies of the lipid class, glycolipids compositions of sea cucumber. Methods: This study was conducted to determine the lipid class and glycolipid compositions of dried sea cucumber, A. japonicus, and analyze fatty acid compositions of Monogalactosyl Diglycerides (MGDG), Steryl Glycosides (SG) and Sulfoquinovosyl Diglycerides (SQDG). Total lipids of sea cucumber were extracted by Bligh and Dyer method and Sep-Pak Silica plus long cartridge, and Thin Layer Chromatography (TLC) silica gel G-60 F254 was used for the separation of different lipid classes and glycolipid compositions. The composition of fatty acids was analyzed by GC. Results & Conclusion: The level of total lipids in the dried sea cucumber, Apostichopus japonicus, was 4 ± 1% of dry weight (w/w) and the amount of neutral lipids, glycolipids and phospholipids was 31 ± 1%, 29 ± 1% and 40 ± 1% of the total lipids (w/w), respectively. MGDG, SG and SQDG were the major glycolipids, and the contents were 37.5 ± 0.3%, 33.8 ± 0.5% and 23.6 ± 0.7% of the total glycolipids (w/w), respectively and significantly higher than other glycolipids (p < 0.05). SQDG contained much higher Arachidonic Acid (AA), Eicosapentaenoic Acid (EPA) and MGDG contained higher Docosahexaenoic Acid (DHA) compared with SG (p < 0.05). Further investigation is required to understand the positional distribution of fatty acids and molecular species in MGDG, SG and SQDG in detail.

Structure of the plant photosystem I.

Plant photosystem I (PSI) is one of the most intricate membrane complexes in nature. It comprises two complexes, a reaction center and light-harvesting complex (LHC), which together form the PSI-LHC supercomplex. The crystal structure of plant PSI was solved with two distinct crystal forms. The first, crystallized at pH 6.5, exhibited P21 symmetry; the second, crystallized at pH 8.5, exhibited P212121 symmetry. The surfaces involved in binding plastocyanin and ferredoxin are identical in both forms. The crystal structure at 2.6 Å resolution revealed 16 subunits, 45 transmembrane helices, and 232 prosthetic groups, including 143 chlorophyll a, 13 chlorophyll b, 27 β-carotene, 7 lutein, 2 xanthophyll, 1 zeaxanthin, 20 monogalactosyl diglyceride, 7 phosphatidyl diglyceride, 5 digalactosyl diglyceride, 2 calcium ions, 2 phylloquinone, and 3 iron sulfur clusters. The model reveals detailed interactions, providing mechanisms for excitation energy transfer and its modulation in one of nature's most efficient photochemical machine.

Relationships between lipase-treated wheat lipid classes and their functional effects in wheat breadmaking

Fractionation of lipase-treated wheat lipids showed that polar lipase-reaction products were responsible for their positive functional effects in breadmaking. The results allowed the conclusion that an optimal baking lipase preferably hydrolyzes monogalactosyl diglycerides and N-acyl phosphatidyl ethanolamine, but has only moderate activity towards digalactosyl diglycerides. Synergistic effects of digalactosyl diglycerides and their products digalactosyl monoglycerides (molar proportion 1:1) provide even a greater bread volume increase. Reconstitution baking (defatted flour plus lipid or lipid fraction added) partly provided contradictory results. 100% polar lipase-treated lipids were less active than untreated polar dough lipids plus polar flour lipids. Combinations of non-polar and polar lipase-treated lipids were even more active than the polar ones alone. It appears that the polar reaction products of baking lipases need the presence of unmodified lipids or non-polar lipids to provide optimal functional effects. The present data suggests that synergistic effects between different lipid classes might play a key role in the mechanism of action of baking lipases.

Anti-herpes simplex virus activities of monogalactosyl diglyceride and digalactosyl diglyceride from Clinacanthus nutans, a traditional Thai herbal medicine

ObjectiveTo evaluate the monogalactosyl diglyceride (MGDG) and digalactosyl diglyceride (DGDG) from Clinacanthus nutans (C. nutans) for their in vitro antiviral activities against herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) by plaque reduction assay. MethodsMGDG and DGDG were extracted with chloroform from C. nutans leaves. MGDG and DGDG were separated from chloroform crude extract using column chromatography, characterized by thin layer chromatography and quantified by high performance liquid chromatography. The anti HSV-1 and 2 activity against pre-treatment and post-treatment of the compounds was evaluated using plaque reduction assay. The cytotoxicity of the extract and the compounds on Vero cells were performed by MTT assay. ResultsMGDG and DGDG obtained by column chromatography showed identical profiles as standard MGDG and standard DGDG using thin layer chromatography and high performance liquid chromatography. MGDG and DGDG from C. nutans showed 100% inhibition of HSV-1 replication at the post step of infection at noncytotoxic concentration with IC50 values of 36.00 and 40.00 μg/mL, and HSV-2 at 41.00 and 43.20 μg/mL, respectively. Moreover, MGDG and DGDG from C. nutans were demonstrated to have anti-herpes simplex activity at the same level as standard synthetic compounds. In contrast, pre-treatment of Vero cells with MGDG and DGDG before HSV-1 and HSV-2 infection did not show inhibitory effect against these viruses. MGDG and DGDG exhibited antiviral activity against HSV-1 with selectivity index of 26.00 and 23.00 and HSV-2 of 23.30 and 21.30. ConclusionsMGDG and DGDG from C. nutans, a traditional Thai herbal medicine illustrated inhibitory activity against HSV-1 and HSV-2, probably by inhibiting the late stage of multiplication, suggesting their promising use as anti-HSV agents.

Impact of Composition upon Ordered Membrane Domain(“Raft”) Formation by Lipids from Pathogenic Bacteria

Co-existing ordered (raft) and disordered membrane domains have been indentified in the outer membrane of the pathogenic bacterium Borrelia burgdorferi, the bacterium which causes Lyme disease. Co-existing ordered and disordered membranes can also be detected into B. burgdorferi lipid extracts. However, unlike eukaryotic cells, B. burgdorferi lack sphingolipids, which are crucial component of eukaryotic rafts. In order to understand the basis of domain formation in this organism we have isolated the major lipids of B. burgdorferi by thin layer chromatography, and have initiated studies of their physical properties when dispersed in aqueous solutions. We have found that mixtures of the predominant lipids found in B. burgdorferi, namely, ACGal, a lipid in which a fatty acyl chain and cholesterol are linked to galactose, monogalactosyldiglyceride (MGalD) with phosphatidylcholine (PC) can form ordered domains with thermal stabilities similar to that in whole lipid extracts. However, for individual lipid aqueous dispersions domain formation and/or stability is very different than in whole lipid extracts. Combinations of B. burgdorferi lipids are being studied to identify which lipid are necessary and sufficient for the formation of co-existing ordered and disordered domains in this bacterium and related ones.

Composition and Antiradical Power of Syzygium aromaticum Lipids

2) determine the total phenolic content and in vitro radical scavenging activity of CO. The results from the present study will be used to develop novel edible oil products rich in bioactive molecules with a desirable shelf life. The proportion of lipid classes present in CO as well as the R f values of the subclasses are shown in Table 1. The level of NL was the highest (ca. 94.7%), followed by GL (0.76%) and PL (0.39%). The data are in agreement with Suzuki et al. [13] who analyzed the lipid classes of clove lipidic extract. Subclasses of NL contained triacylglycerol (TG), free fatty acids (FFA), diacylglycerol (DG), esterified sterols (STE), and monoacylglycerol (MG) in decreasing order. A significant amount of TG was found (ca. 96.6% of total NL) followed by a relatively low level of FFA (ca. 1.4% of total NL), while DG and STE were recovered in lower levels. The subclasses of GL found in CO were sulfoquinovosyl diacylglycerol (SQD), digalactosyl diglycerides (DGD), cerebrosides (CER), steryl glycosides (SG), monogalactosyl diglycerides (MGD), and esterified steryl glycosides (ESG) as presented in Table 1. The proportion of each component was estimated by lipid-carbohydrate determination. CER, SG, and ESG were the prevalent components and made up about 92% of the total GL. The PL subclasses in CO were separated into four major fractions via TLC. The TLC fractions of PL revealed that the predominant PL subclasses were PC followed by PE, PI, and PS (Table 1). About half of the total PL was in PC and a quarter was in PE, while PI and PS were isolated in smaller quantities. The fatty acid profiles of CO and lipid classes (NL, GL, and PL) are presented in Table 2. According to the results, nine fatty acids were identified in CO. Linoleic and oleic acids were the main fatty acids in CO. Both fatty acids comprise together about 80% of the total FAME. The cold-pressed oil contained significant levels of monounsaturated fatty acids (MUFA, 39.7 g/100 g total fatty acids), which is comparable to cold pressed hemp, cranberry, blueberry, onion, and milk thistle seed oils but is much lower than the 81 and 82% in carrot and parsley cold pressed seed oils 14, 15.

Differential response of fatty acid composition in the different lipid classes from particulate matter in a high arctic fjord (Kongsfjorden, Svalbard)

Lipid classes and the respective fatty acid composition of natural particulate matter were studied on a seasonal basis in the Arctic fjord Kongsfjorden (Svalbard) during the early summer of 2006 and the spring, summer of 2007. Polar lipids were the major lipid class most of the times in 2006 and at all times in 2007. Among neutral lipids triglycerides were dominant. Polar lipids were divided into glycolipids (chloroplast membranes) and phospholipids (live cell membranes). Glycolipids were further divided into monogalactosyldiglycerides (MGDG), the major glycolipid, followed by digalactosyldiglycerides (DGDG) and Sulfoquinovosyldiglycerides (SQDG). In 2007, changes in both polar lipid constituents showed similar increasing trend from May to mid June but subsequently showed opposite trends from July to September. The seasonal pattern of particulate glycolipids was one of the low concentrations of MGDG in June followed by an increase between late June and September. SQDG exhibited a similar trend while DGDG displayed an opposing trend. In 2007, fatty acid composition of phospholipids, glycolipids and neutral lipids was dominated by saturated acids at all times followed by mono unsaturated acids and polyunsaturated acids with docosahexaenoic acid (DHA, 22:6n-3), eicosapentaenoic acid (EPA, 20:5n-3) and 18:5n-3 as major contributors. Glycolipid fatty acid pattern differed from that of phospholipids, showing a more important contribution of 18:5n-3. Neutral lipid composition differed from the other two classes by a larger contribution of 16:1n-5 and percentages of EPA, DHA, 18:5 and 18:4n-3 lower than in the two structural classes. Factorial correspondence analysis (FCA) of the fatty acid composition of all classes illustrated a seasonal transition in species composition and/or physiological states for the phospholipids and the different processes of chloroplast membrane adaptation in relation to taxonomic changes for the glycolipids. Neutral lipid changes were more complex because of the combined influence of growth rates, nutrient limitations and community shifts. The differential response of the different lipid classes is discussed in relation with the complex interactions between community structure, environmental adaptation and metabolic processes.

Pleiotropic increases in free non‐polar lipid, glycolipid and phospholipid contents in waxy bread wheat (Triticum aestivum L.) grain

Diethyl ether-extractable free lipid (FL), non-polar or neutral lipid (NL), glycolipid (GL) and phospholipid (PL) contents and water-saturated 1-butanol (WSB)-extractable non-starch lipid (NSL)-monogalactosyldiglyceride (MGDG), digalactosyldiglyceride (DGDG) and phosphatidylcholine (PC)-contents in bread wheat (Triticum aestivum L.) grain were evaluated to elucidate the possible influence of the Wx-D1 gene on the lipid composition. Waxy near-isogenic lines with a non-functional Wx-D1d allele showed consistently increased NL, GL and PL contents among FL and MGDG, DGDG and PC contents among NSL compared with non-waxy near-isogenic lines with a functional Wx-D1a allele throughout three growing/harvest seasons. However, the proportion of NL, GL and PL among FL was not influenced by the non-waxy/waxy state of the endosperm. The nearly non-functional Wx-D1f allele influenced the FL and NL contents in a similar manner to the non-functional allele across two seasons, while the partly functional Wx-D1g allele only affected the NL content. The Wx-D1 locus has pleiotropic effects on the diethyl ether-extractable FL, NL, GL and PL contents and WSB-extractable MGDG, DGDG and PC contents of bread wheat grain. The non-functional Wx-D1d allele causes an increase in the levels of these lipids.

Kinetic properties of mouse pancreatic lipase-related protein-2 suggest the mouse may not model human fat digestion

Genetically engineered mice have been employed to understand the role of lipases in dietary fat digestion with the expectation that the results can be extrapolated to humans. However, little is known about the properties of mouse pancreatic triglyceride lipase (mPTL) and pancreatic lipase-related protein-2 (mPLRP2). In this study, both lipases were expressed in Pichia Pastoris GS115, purified to near homogeneity, and their properties were characterized. Mouse PTL displayed the kinetics typical of PTL from other species. Like mPTL, mPLRP2 exhibited strong activity against various triglycerides. In contrast to mPTL, mPLRP2 was not inhibited by increasing bile salt concentration. Colipase stimulated mPLRP2 activity 2- to 4-fold. Additionally, mPTL absolutely required colipase for absorption to a lipid interface, whereas mPLRP2 absorbed fully without colipase. mPLRP2 had full activity in the presence of BSA, whereas BSA completely inhibited mPTL unless colipase was present. All of these properties of mPLRP2 differ from the properties of human PLRP2 (hPLRP2). Furthermore, mPLRP2 appears capable of compensating for mPTL deficiency. These findings suggest that the molecular mechanisms of dietary fat digestion may be different in humans and mice. Thus, extrapolation of dietary fat digestion in mice to humans should be done with care.

Ichthyotoxicity of gymnodinioid dinoflagellates: PUFA and superoxide effects in sheepshead minnow larvae and rainbow trout gill cells

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 426:213-224 (2011) - DOI: https://doi.org/10.3354/meps09036 Ichthyotoxicity of gymnodinioid dinoflagellates: PUFA and superoxide effects in sheepshead minnow larvae and rainbow trout gill cells Ben D. Mooney1,*, Juan José Dorantes-Aranda1, Allen R. Place2, Gustaaf M. Hallegraeff1 1University of Tasmania, Institute for Marine and Antarctic Studies, Private Bag 55, Hobart, Tasmania 7001, Australia 2Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Sciences, Baltimore, Maryland 21202, USA *Email: ben.mooney@utas.edu.au ABSTRACT: While 24 h exposure of sheepshead minnow fish larvae to purified monogalactosyl diglyceride (MGDG) lipids, containing octadecapentaenoic acid (OPA) exclusively or as a mixture of octadecatetraenoic acid, eicosapentaenoic acid, and OPA (OTA-EPA-OPA), caused sluggish swimming and gulping, it produced no mortalities even at concentrations up to 120 mg l–1. In contrast, comparable concentrations and exposure times caused significant reductions in viability of rainbow trout gill cells. Pure EPA was the most harmful to gill cells (up to 98.5% viability loss in 60 h) followed by OPA-rich MGDG (45% loss), with OTA-rich MGDG (37% loss) the least toxic. OPA-pure MGDG was non-toxic to rainbow trout gill cells; however, surprisingly, pure palmitic acid was harmful (40% viability loss), and we conclude that gill cell line toxicity of the OPA-rich MGDG fraction was caused by admixture with palmitic acid. Screening of 15 Kareniaceae dinoflagellate species demonstrated that these species are low (on average 10 times less) producers of superoxide compared to the ichthyotoxic raphidophyte Chattonella marina. No mortality of sheepshead minnow fish larvae occurred when exposed to superoxide alone or superoxide combined with either OPA-rich MGDG or OTA-rich MGDG. Superoxide showed a slight impact on viability of rainbow trout gill cells. In conclusion, synergistic interactions between free fatty acids and reactive oxygen species as previously claimed for raphidophytes could not be confirmed. Gill damaging effects from EPA were conclusively demonstrated, however; when these co-occurred with OTA, a higher loss of viability was observed (up to 37%), suggesting a magnified toxic effect. Contradictory literature claims as to the ichthyotoxicity of OPA (nontoxic in our work) may relate to the presence of chemical impurities. KEY WORDS: Kareniaceae · Ichthyotoxicity · Octadecapentaenoic acid · OPA · Polyunsaturated fatty acid · PUFA· Superoxide Full text in pdf format PreviousNextCite this article as: Mooney BD, Dorantes-Aranda JJ, Place AR, Hallegraeff GM (2011) Ichthyotoxicity of gymnodinioid dinoflagellates: PUFA and superoxide effects in sheepshead minnow larvae and rainbow trout gill cells. Mar Ecol Prog Ser 426:213-224. https://doi.org/10.3354/meps09036 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 426. Online publication date: March 28, 2011 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2011 Inter-Research.

Brachybacterium saurashtrense sp. nov., a halotolerant root-associated bacterium with plant growth-promoting potential

A Gram-positive-staining, aerobic, non-motile, coccoid shaped, halotolerant bacterium (strain JG 06(T)) was isolated from the roots of Salicornia brachiata, an extreme halophyte. Phylogenetic analysis based on 16S rRNA gene sequence showed that the novel strain had sequence similarities of 99.2% to Brachybacterium paraconglomeratum JCM 11608(T), 99.0% to Brachybacterium conglomeratum DSM 10241 and 98.2% to Brachybacterium faecium DSM 4810(T). DNA-DNA hybridization with B. paraconglomeratum DSM 46341(T), B. conglomeratum DSM 10241(T), B. faecium DSM 4810(T), Brachybacterium tyrofermentans DSM 10673(T), Brachybacterium alimentarium DSM 10672(T), Brachybacterium fresconsis DSM 14564(T), Brachybacterium sacelli DSM 14566(T) and Brachybacterium muris DSM 15460(T) resulted in reassociation values of 36.2%, 36.5%, 35.8%, 27.6%, 27.9%, 28.2%, 28.7% and 11.2%, respectively. The peptidoglycan type of strain JG 06(T) was variant A4γ. The menaquinone content was MK7 (100%). The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, monogalactosyl diglyceride, three unidentified phospholipids and three glycolipids. The predominant fatty acid was anteiso-C(15:0) (52.07%); significant amounts of iso-C(16:0)(12.38%), iso-C(15:0 )(8.59%) and anteiso-C(17:0)(10.03%) were also present. The G+C content of the DNA was 73.0 mol%. The strain formed a growth pellicle in nitrogen-free semisolid NFb medium containing NaCl at levels of up to 4% (w/v) and reduced acetylene to ethylene, a result indicative of N(2) fixation. In nutrient broth medium the novel strain grew at NaCl concentrations up to 15% (w/v). It also had the ability to produce indole-3-acetic acid (IAA) and siderophores, utilized 1-aminocyclopropane-1-carboxylate (ACC) as a sole source of nitrogen and possessed the ACC deaminase enzyme. On the basis of physiological, biochemical data and phylogenetic analyses, strain JG 06(T) should be placed in the genus Brachybacterium. Strain JG 06(T) represents a novel species of the genus Brachybacterium for which the name Brachybacterium saurashtrense sp. nov. is proposed (type strain JG 06(T)=DSM 23186(T)=IMCC 252(T)).

Continuous measurement of galactolipid hydrolysis by pancreatic liplytic enzymes using the pH-stat technique and a medium chain monogalactosyl diglyceride as substrate.

Continuous measurement of galactolipid hydrolysis by pancreatic liplytic enzymes using the pH-stat technique and a medium chain monogalactosyl diglyceride as substrate.

Continuous measurement of galactolipid hydrolysis by pancreatic lipolytic enzymes using the pH-stat technique and a medium chain monogalactosyl diglyceride as substrate

Galactolipids are the main lipids from plants and galactolipases play a major role in their metabolism. These enzymes were however poorly studied so far and only few assays have been developed. A specific and continuous galactolipase assay using synthetic medium chain monogalactosyl diacylglycerol (MGDG) as substrate was developed using the pH-stat technique and recombinant human (rHPLRP2) and guinea pig (rGPLRP2) pancreatic lipase-related protein 2 as model enzymes. PLRP2s are the main enzymes involved in the digestion of galactolipids in the gastrointestinal tract. Monogalactosyl di-octanoylglycerol was mixed with bile salt solutions by sonication to form a micellar substrate before launching the assay. The nature of the bile salt and the bile salt to MGDG ratio were found to significantly affect the rate of MGDG hydrolysis by rHPLRP2 and rGPLRP2. The maximum galactolipase activity of both enzymes was recorded with sodium deoxycholate (NaDC) and at a NaDC to MGDG ratio of 1.33 and at basic pH values (8.0–9.0). The maximum rates of hydrolysis were obtained using a MGDG concentration of 10 − 2 M and calcium chloride was found to be not necessary to obtain the maximum of activity. Under these conditions, the maximum turnovers of rGPLRP2 and rHPLRP2 on mixed NaDC/MGDG micelles were found to be 8000 ± 500 and 2800 ± 60 μmol/min/mg (U/mg), respectively. These activities are in the same order of magnitude as the activities on triglycerides of lipases and they are the highest specific activities ever reported for galactolipases. For the sake of comparison, the hydrolysis of mixed bile salt/MGDG micelles was also tested using other pancreatic lipolytic enzymes and only native and recombinant human carboxyl ester hydrolase were found to display significant but lower activities (240 ± 17 and 432 ± 62 U/mg, respectively) on MGDG.

Isotopic Replacement of Pigments and a Lipid in Chlorosomes fromChlorobium limicola: Characterization of the Resultant Chlorosomes

Pigments including bacteriochlorophyll (BChl) c, carotenoids, and a trace of BChl a together with a lipid, monogalactosyl diglyceride (MGDG), were extracted with chloroform/methanol (1:1 v/v) from an aqueous suspension (50 mM Tris-HCl, pH 8.0) of chlorosomes from Chlorobium limicola; other lipids and proteins were left behind in the aqueous layer by funnel separation. The chloroform layer was dried by purging N2 gas, dissolved in methanol, and rapidly injected into the aqueous layer to reassemble chlorosomes. This technique has been developed to replace one-half of the inherent 12C-BChl c by 13C-BChl c to identify the intermolecular 13C...13C magnetic dipole correlation peaks (that are supposed to reduce their intensities to one-fourth by reducing the 13C-BChl c concentration into one-half) and to determine the structure of BChl c aggregates in the rod elements by means of solid-state NMR spectroscopy. The isotopically replaced chlorosomes were characterized (1) by sucrose density gradient centrifugation, zeta potential measurement, electron microscopy, and dynamic light scattering measurement to determine the morphology of chlorosomes, (2) by 13C NMR spectroscopy, electronic absorption and circular dichroism spectroscopies, and low-angle X-ray diffraction to determine the pigment assembly in the rod elements, and (3) by subpicosecond time-resolved absorption spectroscopy to determine the excited-state dynamics in the pigment assembly. The results characterized the reassembled chlorosomes to have (1) similar but longer morphological structures, (2) almost the same pigment assembly in the rod elements, and (3) basically the same excited-state dynamics in the pigment assembly.