Biomedical subjects

V Wray

Publications and source records attributed to V Wray.

At least 91 records · Page 5Linked to original sources

PubMed1995

Mutational effects on the spectroscopic properties and biological activities of oxidized bovine adrenodoxin, and their structural implications.

Of the aromatic 1H-NMR signals of oxidized bovine adrenodoxin only those of His56 showed intrinsic chemical shift changes upon replacement of Tyr82 by Ser or Leu, that must arise from a loss of a through-space ring-current effect of the tyrosine ring in these mutants. Thus, of the three His residues contained in adrenodoxin, His56 is closest to Tyr82, and hence to the highly acidic determinant region of adrenodoxin that is the interaction site for adrenodoxin reductase and P-450. The strong dependence of the fluorescence intensity of Tyr82 on the residue in position 56 supported this observation. As a consequence of this, the effects of replacement of His56 by Gln or Thr on cytochrome c reduction and cytochromes P-450(11 beta) (CYP11B1)-dependent and P-450scc (CYP11A1)-dependent substrate conversions were studied. No influence on Vmax values was observed for all reactions mediated by the mutants, implying His56 does not play a decisive role in the intramolecular or intermolecular electron transfer. In contrast, the Km values were increased, as was the Ks value for binding of CYP11A1 to the [H56T]adrenodoxin. The secondary structure deduced from further NMR data of adrenodoxin was compared with that of other ferredoxins. Tyr82 is in a region of the molecule containing no secondary-structure elements. The data for Tyr82 are in keeping with the biological activities and suggests it is in a flexible, solvent-exposed region of the molecule.

Adrenodoxin↗

PubMed1995

Identification and structural characterization of a mannose-6-phosphate containing oligomannosidic N-glycan from human erythropoietin secreted by recombinant BHK-21 cells.

A sialidase resistant mono-charged N-glycan was isolated from glycosylation site I (Asn-24) of recombinant human erythropoietin expressed from baby hamster kidney (BHK-21) cells and constituted approximately 2-4% of the oligosaccharide material at this glycosylation site. Mass spectrometry and both 1- and 2-dimensional NMR techniques revealed a high mannose type structure (Man6) with a phospho-diesterbridged N-acetylglucosamine as follows: [formula: see text]

Animals↗

PubMed1995

Triterpenoid saponins from the aerial parts of Aster bellidiastrum.

Four major triterpenoid saponins were isolated from the aerial parts of Aster bellidiastrum. The structures were elucidated from their NMR and mass spectral data, and from derivatization. One is a new compound with the structure 3-O-beta-D-glucopyranosyl-2 beta,3 beta,16 alpha,23-tetrahydroxyolean-12-en-28- oic acid 28-O-beta-D-xylopyranosyl(1-->4)-alpha-L-rhamnopyranosyl(1-->2)-beta- D-fucopyranoside, while the three others have been previously identified in extracts from various Bellis species.

Carbohydrate Sequence↗

PubMed1995

Structure elucidation of a glycoside of 2 beta, 3 beta, 23-trihydroxy-16-oxoolean-12-en-28-oic acid from Bellis bernardii using mass spectrometry for the sugar sequence determination.

The structure of a novel saponin, possessing an unusual aglycone named bellisonic acid and isolated from whole plants of Bellis bernardii, has been elucidated by modern ms and nmr techniques as 3-O-alpha-L-rhamnopyranosyl-2 beta, 3 beta, 23-trihydroxy-16-oxoolean-12-en-28-oic acid 28-alpha-L-rhamnopyranosyl(1-->3)-O-beta-D-xylopyranosyl(1-->4)-alpha-L- rhamnopyranosyl(1-->2)-beta-D-fucopyranoside [1]. Ms procedures of general applicability allowed unambiguous sugar sequence determination from very small amounts of material.

Carbohydrate Conformation↗

PubMed1995

The main saponins from the aerial parts and the roots of Solidago virgaurea subsp. virgaurea.

Two new (3, 4) and two known (1, 2) genuine acylated bisdesmosidic triterpenoid glycosides of polygalacic acid (2 beta, 3 beta, 16 alpha, 23-tetrahydroxyolean-12-en-28-oic acid) were isolated from the aerial parts, as well as from the roots, of Solidago virgaurea L. subsp. virgaurea. The structures of these esters were elucidated as 4-O-fucopyranosyl-acylated compounds (1, 2, 3, 4) of 28-[O-alpha-L-rhamnopyranosyl-(1-->3)-O-beta-D-xylopyranosyl- (1-->4)-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-fucopyranosyl]-glycosid es of 3-O-[beta-D-glucopyranosyl]-polygalacic acid (5), and 3-O-[O-beta-D-glucopyranosyl-(1-->3)-beta-D-glucopyranosyl]- polygalacic acid (6).

Carbohydrate Sequence↗

PubMed1995

Levels of a terpenoid glycoside (blumenin) and cell wall-bound phenolics in some cereal mycorrhizas.

Four cereals, Hordeum vulgare (barley), Triticum aestivum (wheat), Secale cereal (rye), and Avena sativa (oat), were grown in a defined nutritional medium with and without the arbuscular mycorrhizal fungus Glomus intraradices. Levels of soluble and cell wall-bound secondary metabolites in the roots of mycorrhizal and nonmycorrhizal plants were determined by high-performance liquid chromatography during the first 6 to 8 weeks of plant development. Whereas there was no difference in the levels of the cell wall-bound hydroxycinnamic acids, 4-coumaric and ferulic acids, there was a fungus-induced change of the soluble secondary root metabolites. The most obvious effect observed in all four cereals was the induced accumulation of a terpenoid glycoside. This compound was isolated and identified by spectroscopic methods (nuclear magnetic resonance, mass spectrometry) to be a cyclohexenone derivative, i.e. blumenol C 9-O-(2'-O-beta-glucuronosyl)-beta-glucoside. The level of this compound was found to be directly correlated with the degree of root colonization.

Avena↗

PubMed1995

Solution structure of the hydrophilic region of HIV-1 encoded virus protein U (Vpu) by CD and 1H NMR spectroscopy.

The HIV-1 specific Vpu is a class I oligomeric membrane phosphoprotein of unknown structure and mechanism. The first experimental evidence for the position of secondary structural elements present in the hydrophilic C-terminal region of Vpu under various solution regimes is reported. CD data for nine overlapping 15 amino-acid fragments and 3 longer fragments indicate the presence of only transitory amounts of stable structure in aqueous solution alone, while with increasing trifluoroethanol content limiting structures were found indicating two helical segments in the hydrophilic region of Vpu. These limiting structures were more precisely defined from a detailed study of Vpu41-58, Vpu52-74 and Vpu63-81, by a combination of 2D 1H NMR spectroscopy, distance geometry, and restrained molecular dynamics and energy minimization calculations. Sets of low-energy conformations compatible with the quantitative NOE data indicate that Vpu41-58 has an alpha-helix from residues 42 to 50 while a second helix is found for Vpu52-74 from residues 57 to 69. Vpu63-81 shows only the presence of a single reverse turn at residues 74 to 77, without any evidence of helix, under the same conditions. From CD measurements the first helix extends back to residue 30 and is connected to the N-terminal anchor of Vpu. Thus the hydrophilic region of Vpu consists of two alpha-helices joined by a flexible region of 6 or 7 residues, which contains the phosphoacceptor sites of Vpu at positions 52 and 56. The second helix is followed by a single reverse turn and a flexible C-terminus.

Amino Acid Sequence↗

PubMed1995

Characterization of a new lipopeptide surfactant produced by thermotolerant and halotolerant subsurface Bacillus licheniformis BAS50.

Strain BAS50, isolated from a petroleum reservoir at a depth of 1,500 m and identified as Bacillus licheniformis, grew and produced a lipopeptide surfactant when cultured on a variety of substrates at salinities of up to 13% NaCl. Surfactant production occurred both aerobically and anaerobically and was optimal at 5% NaCl and temperatures between 35 and 45 degrees C. The biosurfactant, termed lichenysin A, was purified and chemically characterized. A tentative structure and composition for the surfactant are described. Lichenysin A is a mixture of lipopeptides, with the major components ranging in size from 1,006 to 1,034 Da. The lipid moiety contains a mixture of 14 linear and branched beta-hydroxy fatty acids ranging in size from C12 to C17. There are seven amino acids per molecule. The peptide moiety is composed of the following amino acids: glutamic acid as the N-terminal amino acid, asparagine, valine, leucine, and isoleucine as the C-terminal amino acid, at a ratio of 1.1:1.1:1.0:2.8:1.0, respectively. Purified lichenysin A decreases the surface tension of water from 72 mN/m to 28 mN/m and achieves the critical micelle concentration with as little as 12 mg/liter, characterizing the product as a powerful surface-active agent that compares favorably to others surfactants. The antibacterial activity of lichenysin A has been demonstrated.

Amino Acids↗

PubMed1995

Synthesis, solution structure and biological action of PACAP-related peptide.

High quality PACAP-related peptide (PRP), a 29 amino-acid region of the PACAP precursor protein, has been synthesized in quantities sufficient for biological and structural studies. PRP has a distinct biological activity on the gallbladder that is similar to PACAP, but opposite to that of VIP and its related peptide, PHM. Its solution structure has been investigated by circular dichroism spectroscopy and 2D 1H nuclear magnetic resonance spectroscopy. In contrast to the poorly defined structure in aqueous solution alone, the limiting structure, under conditions that mimic a membrane-like environment, possesses stable secondary structure with a helical region between residues 3 and 20, that is terminated by the presence of glycine at residue 21 and is followed by a region of nascent helix. The similarities and differences in the structure of PRP, PACAP27 and GHRH(1-29) are made through comparison of their H alpha chemical shift data and differences in their biological activities assessed.

Amino Acid Sequence↗

PubMed1994

Properties of unusual phospholipids, II: Synthesis, NMR studies and monolayer investigations of diacylglycerophosphocholines containing alpha-branched acyl chains.

Diacylglycerophosphocholines, containing various alpha-branched fatty acids, were synthesized and purified to homogeneity. The influence of the alpha-branched acyl chains on the monolayer packing properties of these phospholipids was studied by the Langmuir-Blodgett film balance technique. NMR investigations were used for conformational studies, including the determination of rotamer populations about the dihedral angles (theta 2, theta 4 and alpha 1) in the glycerol region of the diacylglycerophosphocholines.

Fatty Acids↗

PubMed1994

The structure of human parathyroid hormone from a study of fragments in solution using 1H NMR spectroscopy and its biological implications.

In order to gain insight into the structure of human parathyroid hormone (hPTH), four fragments [hPTH(1-34), hPTH(18-48), hPTH(28-48), and hPTH(53-84)], which cover all regions of the intact hormone, have been investigated by CD and NMR spectroscopy in combination with distance geometry, and restrained molecular dynamics and energy minimization calculations, under a variety of solution conditions. Significantly, all fragments showed little propensity to form stable structures in aqueous solution alone, and it was only on the addition of trifluoroethanol (TFE) that defined structural features were observed. In an extension of earlier work [Klaus et al. (1991) Biochemistry 30, 6936-6942], hPTH(1-34) in 70% trifluoroethanol (TFE) showed two helices that were longer than in 10% TFE, but essentially showed the same characteristics. Although overlap in the 1H NMR spectra prevented the determination of quantitative NOE data for residues 26-30, the combination of the alpha-proton chemical shift data and quantitative NOE data indicated the helices extend from residues 3 to 13 and 15 to 29. No evidence was found for interaction of the two helical regions. The nature and extent of this second helix in the intact hormone were better defined from the data for hPTH(18-48). Under limiting solution conditions, where the fragment assumed its maximum helical content, a well-defined helix was observed between residues 21 and 38 with a possible discontinuity between Leu-28 and Gln-29. There was little evidence of any form of secondary structure between Gly-38 and the terminus of this fragment, Ser-48. In keeping with this result, the shorter fragment, hPTH(28-48), showed little evidence of stable secondary structure on addition of TFE. From the alpha-proton chemical shifts residues 23-27 appeared to sustain helical structure more readily than the rest of molecule under all solution regimes in both hPTH(1-34) and hPTH(18-48). In contrast to the other two longer fragments hPTH(53-84) showed little propensity for helical secondary structure even at the highest TFE concentrations. However, there was evidence that the molecule did adopt a defined three-dimensional structure. Various long-range NOE's were observed in 10% TFE that allowed the calculation of an open tertiary structure consisting of an initial series of turns surrounded by a loop structure of several loose turns.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗

PubMed1994

Structure and physical properties of the extracellular polysaccharide PS-P4 produced by Sphingomonas paucimobilis P4 (DSM 6418).

A new strain, Sphingomonas paucimobilis P4 (DSM 6418), was found during a screening programme for exopolysaccharide-producing bacteria. The highly viscous fermentation broth yields a polysaccharide (up to 10 kg/m3), named PS-P4, and shows thixotropic flow behaviour. In the presence of phosphate ions, PS-P4 forms aqueous gels after heating and cooling at alkaline pH. After isolation and purification of the exopolysaccharide, structural analysis by 1D and 2D 1H NMR spectroscopy and mass spectrometry was performed. The deacylated exopolysaccharide has the following repeating trisaccharide structure:-->4)-beta-D-Glcp-(1-->4)-alpha-L-Rhap-(1-->3)-beta-D- Glcp(1-->Additionally, the presence of ester-bound acetic acid, D-glyceric acid, and (R)-3-hydroxybutyric acid in the native polysaccharide was demonstrated.

Carbohydrate Sequence↗

PubMed1994

A recombinant human immunodeficiency virus type-1 capsid protein (rp24): its expression, purification and physico-chemical characterization.

An expression system has been established in Escherichia coli to facilitate the preparation of the HIV-1 capsid protein in amounts sufficient for structural analysis. A plasmid vector pTCA5, containing the gene for the recombinant HIV-1 capsid protein rp24 under the control of the lambda-PR-promoter, was constructed which gave an expression product that spanned 234 amino acid residues. It differs at the N-terminus from the authentic sequence in that the residues Pro-Ile- are replaced by Met-Asn-Ser-Ala-Met-. Recombinant p24 was produced, as inclusion bodies in E. coli LE392 containing pTCA5, at a level of approximately 15% of the total cellular protein. After dissolution of the inclusion bodies in the acidic urea system, the protein was easily reconstituted in a soluble state by dialysis. The yield of reconstituted and purified protein was 12 mg per liter in rich medium. Recombinant rp24 consists of about 40% alpha-helix and 10% beta-sheet from circular dichroism measurements and the two cysteine residues, within the rp24 sequence, are bridged by a disulfide bond.

Base Sequence↗

PubMed1994

Cyanoglucosides from Osmaronia cerasiformis (Rosaceae).

Three nitrile glucosides have been isolated from a methanolic extract of the leaves of Osmaronia cerasiformis (Torr. & Gray) Greene (Rosaceae, Prunoideae). One is the known sutherlandin (Z-4-beta-D-glucopyranosyloxy-3-hydroxymethylbut-2-ene nitrile); the second is Z-4-beta-glucopyranosyloxy-3-methylbut-2-ene nitrile, which has recently been characterized but whose stereochemistry was not previously determined; the Z-isomer identified here was named osmaronin. The third is the new 4-beta-D-glucopyranosyloxy-2R,3R-epoxy-3-methylbutyronitrile (osmaronin epoxide). The nitrile glucosides occur in the leaves and flowers of the title plant; their aglycone is apparently derived from the aliphatic amino acid L-leucine.

Glucosides↗

PubMed1994

Betacyanins from bracts of Bougainvillea glabra.

Betacyanins from the bracts of Bougainvillea glabra were isolated and characterized by a combination of spectroscopic techniques (DAD-HPLC, NMR, LC-MS, GC-MS, electrospray MS, tandem MS) as gomphrenin I (betanidin 6-O-beta-glucoside) and various derivatives of bougainvillein-v (betanidin 6-O-beta-sophoroside), i.e. mono- and diglucosylsophorosides which are acylated with 4-coumaric and caffeic acid (mono- and diesters). Besides the betacyanins, B. glabra bracts accumulated large amounts of flavonols (kaempferol and quercetin conjugates) reaching ratios of flavonol to betacyanin of 1:1.

Betalains↗

PubMed1994

Triterpenoid saponins from Bellium bellidioides.

A new acylated triterpenoid saponin carrying the rare 2,3-branched glucose at C-28 of the aglycone bayogenin (2 beta, 3 beta, 23-trihydroxyolean-12-en-28-oic acid) was isolated from the whole plants of Bellium bellidioides. The structure was elucidated mainly by high field NMR experiments (1H and 13C NMR, HMBC, HMQC, COSY-45 at 600/150 MHz) as 3-O-beta-D-glucopyranosyl-28-O-[2-O-alpha-L-rhamnopyranosyl-3-O-beta-D- glucopyranosyl-6-O-acetyl-beta-D-glucopyranosyl]-23-O-acetylbayogenin . Additionally, three acylated derivatives of the known bellissaponin BS1 were obtained.

Carbohydrate Sequence↗

PubMed1994

Triterpenoid saponins from Bellis sylvestris, I. Structures of the major deacylsaponins.

Two major saponins from Bellis sylvestris have been isolated and their structures determined, mainly by high-field nmr spectroscopy. One of these [2] was identical with bellissaponin BS1 from Bellis perennis, while the second is a new triterpenoid saponin [1], named besysaponin C12, and identified as 3-O-alpha-L-rhamnopyranosyl-2 beta,3 beta,16 alpha,23-tetrahydroxyolean-12-en-28-oic acid 28-O-beta-D-xylopyranosyl(1-->4)-alpha-L-rhamnopyranosyl(1-->2)-beta-D- fucopyranoside.

Carbohydrate Sequence↗

PubMed1993

Solution structure of pituitary adenylate cyclase activating polypeptide by nuclear magnetic resonance spectroscopy.

The solution structures of the recently discovered neuropeptides PACAP38 and PACAP27 have been investigated in aqueous solution containing varying amounts of trifluoroethanol (TFE) by circular dichroism (CD) spectroscopy and a combination of 2D 1H nuclear magnetic resonance (NMR) spectroscopy, distance geometry, and refined molecular dynamics and energy minimization calculations. In aqueous solution both peptides show only small transitory amounts of stable structure while in 50% TFE they adopt ordered structures. Qualitative NOE data and the use of the chemical shift index of the alpha-protons identified the positions of alpha-helical regions. A set of low-energy conformations compatible with the quantitative NOE data were obtained for both and each set were subjected to RMS analysis to determine the positions of the secondary structure elements. PACAP38 has an initial disordered N-terminal domain of eight amino acids, followed by an alpha-helical structure stretching from Ser-9 to Val-26, which contains a discontinuity between Lys-20 and Lys-21, and in the C-terminal region there is a short alpha-helix between Gly-28 and Arg-34. The structure of PACAP27 mirrors remarkably closely that of PACAP38 and shows no fraying of the C-terminal helix. The physiological significance of the three structural domains (1-8, 9-26, and 27-38) of PACAP38 is shown by a comprehensive review of recent in vitro and in vivo investigations of PACAP analogues. The correspondence of the global structural features of PACAP with other members of this family of peptides (namely, secretin, glucagon, GHRF1-29 and VIP) is demonstrated by inspection of the chemical shift indices of the alpha-protons.

Amino Acid Sequence↗