Purification and characterization of ascorbic acid 2-kinase from Flavobacterium devorans ATCC 10829

Maximum activity for phosphorylating C(2)-OH of the ascorbic acid was observed at the time of 16 h incubation from the culture of Flavobacterium devorans ATCC 10829. The enzyme was purified 1.178-fold, via ammonium sulfate fractionation, Fast Q anion exchange, and phenyl agarose chromatography. Gel chromatography and SDS-polyacrylamide electrophoresis experiments showed that the enzyme is a tetramer with subunit MW of 29 kDa. Among available second substrates, pyrophosphate showed the highest activity. Optimum temperature and pH were 45 degrees C and 5.5, respectively. The enzyme was chemically modified only by diethylpyrocarbonate and 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC), indicating that histidine and carboxylate are in the active site. pH studies showed that two histidines are involved in the binding of the substrates and a carboxylate in catalysis. Therefore, the chemical mechanism of the enzyme is likely that two histidines bind to pyrophosphate and carboxylate, respectively, and a carboxylate acts as a general base.     

A novel sphingoglycolipid containing galacturonic acid and 2-hydroxy fatty acid in cellular lipids of Sphingomonas yanoikuyae

A novel sphingoglycolipid was isolated from Sphingomonas yanoikuyae, and its structure was identified as a galacturonosyl-beta (1-->1)-ceramide. This was a characteristic sphingoglycolipid present in S. yanoikuyae and certain other species of Sphingomonas, such as Sphingomonas mali, Sphingomonas terrae, and Sphingomonas macrogoltabidus, but not in the type species of Sphingomonas, Sphingomonas paucimobilis.     

Isolation of lipid glucuronic acid and N-acetylglucosamine derivatives from a rat fibrosarcoma

Incubation of labeled UDP-GlcUA and UDP-GlcNAc with microsomes of a fibrosarcoma yielded labeled glycolipids resistant to hydrolysis with dilute alkali. These compounds have been tentatively identified as lipid-GlcNAc, lipid-GlcNAc-GlcUA and lipid-tetra and hexasaccharides containing both GlcUA and GlcNAc.     

A novel meta-cleavage product hydrolase from Flavobacterium sp. ATCC27551

The organophosphate degrading (opd) gene cluster of plasmid pPDL2 of Flavobacterium sp. ATCC27551 contains a novel open-reading frame, orf243. This was predicted to encode an alpha/beta hydrolase distantly related to the meta-fission product (MFP) hydrolases such as XylF, PhnD, and CumD. By homology modeling Orf243 has most of the structural features of MFP hydrolases including the characteristic active site catalytic triad. The purified protein (designated MfhA) is a homotetramer and shows similar affinity for 2-hydroxy-6-oxohepta-2,4-dienoate (HOHD), 2-hydroxymuconic semialdehyde (HMSA), and 2-hydroxy-5-methylmuconic semialdehyde (HMMSA), the meta-fission products of 3-methyl catechol, catechol, and 4-methyl catechol. The unique catalytic properties of MfhA and the presence near its structural gene of cis-elements required for transposition suggest that mfhA has evolved towards encoding a common hydrolase that can act on meta-fission products containing either aldehyde or ketone groups.     

Stereospecificity of fatty acid 2-hydroxylase and differential functions of 2-hydroxy fatty acid enantiomers

FA 2-hydroxylase (FA2H) is an NAD(P)H-dependent enzyme that initiates FA α oxidation and is also responsible for the biosynthesis of 2-hydroxy FA (2-OH FA)-containing sphingolipids in mammalian cells. The 2-OH FA is chiral due to the asymmetric carbon bearing the hydroxyl group. Our current study performed stereochemistry investigation and showed that FA2H is stereospecific for the production of (R)-enantiomers. FA2H knockdown in adipocytes increases diffusional mobility of raft-associated lipids, leading to reduced GLUT4 protein level, glucose uptake, and lipogenesis. The effects caused by FA2H knockdown were reversed by treatment with exogenous (R)-2-hydroxy palmitic acid, but not with the (S)-enantiomer. Further analysis of sphingolipids demonstrated that the (R)-enantiomer is enriched in hexosylceramide whereas the (S)-enantiomer is preferentially incorporated into ceramide, suggesting that the observed differential effects are in part due to synthesis of sphingolipids containing different 2-OH FA enantiomers. These results may help clarify the mechanisms underlying the recently identified diseases associated with FA2H mutations in humans and may lead to potential pharmaceutical and dietary treatments. This study also provides critical information to help study functions of 2-OH FA enantiomers in FA α oxidation and possibly other sphingolipid-independent pathways.     

Separation and analysis of free ceramides containing 2-hydroxy fatty acids in Sphingobacterium species

Abstract The occurrence of free ceramides was shown in the chloroform-methanol extractable lipids of 16 strains of Sphingobacterium including three species: S. versatilis, S. multivorum and S. mizutae . The predominant long-chain base was identified as a branched-chain, saturated dihydroxy base with a carbon chain consisting of 17 carbon atoms, while the most abundant fatty acid was 2-hydroxy-13-methyltetradecanoic acid. The major molecular species of the intact ceramides were identified as LCB- d - iso -17 : 0-2-OH iso -15 : 0FA, LCB- d - iso -17 : 0- iso -15 : 0FA and LCB- d -n16 : 0- iso -15 : 0FA.     

Isolation of a trisaccharide containing 2-amino-2-deoxy-D-galacturonic acid from the Bordetella pertussis endotoxin

4-O-(2-Amino-2-deoxy-alpha-D-glucopyranosyl-6-O-(2-amino-2-deoxy-alpha-D-galactopyranuronyl)-D-glucopyranose, a branched-chain trisaccharide, was isolated after hydrolysis of Bordetella pertussis endotoxin with 4 M HCl for 1 h at 100 degrees C. The trisaccharide was present in both polysaccharide moieties of the two constituent lipopolysaccharides of this endotoxin. Its structure was established by analysis of the 400-MHz nuclear magnetic resonance spectrum and by chemical and enzymatic degradation.     

Microbial production of a novel trihydroxy unsaturated fatty acid from linoleic acid

A bacterium isolated from a dry soil sample collected from McCalla, AL, USA, converted linoleic acid to a novel compound, 12,13,17-trihydroxy-9 (Z)-octadecenoic acid (THOA). The organism is a Gram-positive, non-motile rod (0.5 μ m × 2 μ m). It was identified as a species of Clavibacter ALA2. The product was purified by high pressure liquid chromatography, and its structure was determined by ¹H and ¹³C nuclear magnetic resonance and Fourier transform infrared spectroscopies, and by mass spectrometer. Maximum production of THOA with 25% conversion of the substrate was reached after 5–6 days of reaction. THOA was not further metabolized by strain ALA2. This is the first report of a 12,13,17-trihydroxy unsaturated fatty acid and its production by microbial transformation. Some dihydroxy intermediates were also detected. THOA has a structure similar to those of known plant self-defense substances. Received 13 January 1997/ Accepted in revised form 05 May 1997     

Isolation and biochemical characterization of delta-aminolevulinic acid dehydratase from Streptomyces yokosukanensis ATCC 25520

In this study, delta-aminolevulinic acid dehydratase from Streptomyces yokosukanensis ATCC 25520, producer of an unusual purine riboside antibiotic called nebularine, was purified and characterized. Purification procedures involved with ammonium sulphate precipitation and gel filtration techniques by use of Sephacryl S-200. After gel filtration a 90.76-fold purification was obtained. The maximum enzymic activity was observed in the supernatant after 100% precipitation. According to the data obtained from investigation, the enzyme was found to be a single polypeptide having molecular mass around 34.8 kDa. This was determined by SDS-PAGE. Its optimal temperature around 45 degrees C, and optimal pH was found to be 8.0. Some heavy metals, Pb2+, Zn2+, Fe3+, Co2+, Mn2+, Mg2+ inhibited its activity between 20-51%, Ni2+ increased its activity up to 15%.     

Synthesis of novel glycophanes derived from glucuronic acid by ring closing alkene and alkyne metathesis

Cyclophanes and their analogues are of interest in bioactive molecule development and in biomimetic, supramolecular and materials chemistry. Novel hybrids of sugars and cyclophanes (glycophanes) have been prepared via the coupling of alkenyl and alkynyl glucopyranosiduronic acids with phenylene-1,4-diamine and xylene-1,4-diamine and subsequent intramolecular metathesis. Structural studies showed that the geometric arrangements of the sugar groups in the macrocycles containing secondary amides differ from those in macrocycles that contain tertiary amides. This is due to the amides adopting different configurational preferences. The compounds had low solubility in water, precluding an investigation of their recognition phenomena in this medium.     

The species-specific cell-binding site of the aggregation factor from the sponge Microciona prolifera is a highly repetitive novel glycan containing glucuronic acid, fucose, and mannose

Species-specific adhesion of dissociated cells from the marine sponge Microciona prolifera is mediated by a Mr = 2 x 10(7) proteoglycan-like aggregation factor (MAF) via two highly polyvalent functional domains, a cell-binding and a self-interaction domain. Glycopeptide N-glycosidase F release of a major glycan of Mr = 6.3 gamma 10(3) (G-6) from the MAF protein core resulted in the loss of cell binding activity, indicating a role of this polysaccharide molecule in MAF-cell association. The G-6 glycan was isolated and purified after complete Pronase digestion of MAF using gel electrophoresis, gel filtration, and ion exchange chromatography. Quantification of the amount of carbohydrate recovered in G-6 showed that one MAF molecule has about 950 repeats of this glycan. In its monomeric state G-6 did not display any measurable binding to cells (K alpha less than or equal to 10(3) M-1). Intermolecular cross-linking of the G-6 glycan with glutaraldehyde resulted, however, in the concomitant recovery of polyvalency (about 2200 repeats of G-6 per polymer of Mr greater than or equal to 1.5 x 10(7) and species-specific high cell binding affinity (K alpha = 1.6 x 10(9) M-1) but not of the MAF-MAF self-interaction activity. Thus, the G-6 glycan is the multiple low affinity cell-binding site involved in cell-cell recognition and adhesion of sponge cells. The G-6 glycan has 7 glucuronic acids, 3 fucoses, 2 mannoses, 5 galactoses, 14 N-acetylglucosamines, 2 sulfates, and 1 asparagine. Such a unique chemical composition indicates a new type of structure which includes features of glycosaminolycans and N-linked polysaccharides.