Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Optical Rotation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 901 records · Page 50Linked to original sources
PubMed1991

Toxin production in Pyrenophora teres, the ascomycete causing the net-spot blotch disease of barley (Hordeum vulgare L.).

Toxin production in a large number of Pyrenophora teres isolates have been investigated. During fungal growth, the pH of the medium decreases from 6.5 to about 3.0. Aspergillomarasmine A is the major toxin excreted into the culture medium. Nonenzymatic acid-catalyzed conversion of aspergillomarasmine A to anhydroaspergillomarasmine A proceeds at low pH and is prevented by repeated titration of the culture medium to pH 6.5. The four possible stereoisomers of N-(2-amino-2-carboxyethyl)aspartic acid have been chemically synthesized and their absolute configuration determined. From circular dichroism and NMR spectroscopy and by measurements of specific optical rotation, the LL-form is identified as the stereoisomer produced by P. teres. Biosynthetic experiments using radioisotopes demonstrate that the LL-isomer of N-(2-amino-2-carboxyethyl) aspartic acid is a direct precursor of aspergillomarasmine A. Consequently, L-configuration is assigned to the two corresponding asymmetric carbon atoms of aspergillomarasmine A. This is in contrast to earlier reports which had indicated D configuration. The phytotoxicity of anhydroaspergillomarasmine A is comparable with that of L-aspartic acid, whereas LL-N-(2-amino-2-carboxyethyl)aspartic acid exerts strong phytotoxicity in the bioassays as shown previously for aspergillomarasmine A. The amount of LL-N-(2-amino-2-carboxyethyl)aspartic acid which accumulates in the P. teres cultures is low, indicating that aspergillomarasmine A is the toxin which plays the major role in the pathological changes associated with the barley net-spot blotch disease.

Ascomycota↗
PubMed1990

[Chemical studies on polysaccharide of Achyeanthes bidentata].

A peptide-polysaccharide, ABAB showing immunological activity was isolated from Achyeanthes bidentata Bl. It was shown to be homogeneous by HPLC and optical rotation analysis. Its molecular weight was estimated to be 2.3 x 10(4). It composed of D-glucuronic acid, D-galactose, D-galacturonic acid, L-arabinose and L-rhamnose in molar ratio of 12:2:3:1:1. Reduction of carboxyl groups, methylation analysis, periodate oxidation, Smith degradation and IR analysis showed that ABAB possesses a main chain composed of (1----4)-D-glucuronic acid and (1----4)-D-galacturonic acid residues. The non-reducing terminal residues in the side chains were L-arabinose and L-rhamnose. ABAB contained 24.1% of peptides composed of glycine, glutamic acid, aspartic acid and serine.

Drugs, Chinese Herbal↗
PubMed1990

[Chemical analysis and immunochemical characterization of serotype-specific antigens from the strains of Actinobacillus actinomycetemcomitans which were frequently found in the periodontal pockets of the patients of localized juvenile periodontitis].

Serotype-specific polysaccharide antigens of Actinobacillus actinomycetemcomitans ATCC 29523 (serotype a), Y4 (serotype b) and NCTC 9710 (serotype c) were extracted from whole cells by autoclaving. The extracts were purified by chromatography on DEAE-Sephadex A-25 and Sephacryl S-300 columns. The purified polysaccharide antigens formed a single precipitin band with the corresponding anti-a, b or c serum on immunodiffusion. Analysis of component sugars by GLC, HPLC, GLC-MS, NMR together with specific optical rotation data showed that the serotype a antigen consisted of 6-Deoxy-D-talose, the serotype b antigen consisted of L-rhamnose and D-fucose, and the serotype c antigen consisted of 6-Deoxy-L-talose. Structural analysis indicated that these antigens were composed of closely related repeating units, -3)-6-deoxy-alpha-D-Talp-(1-2)-6-deoxy-alpha-D-Talp-(1- (serotype a), -3)-alpha-D-Fucp-(1-2)-beta-L-Rhap-(1- (serotype b) and -3)-6-deoxy-alpha-L-Talp-(1-2)-6-deoxy-alpha-L-Talp-(1- (serotype c). 13C and 1H-NMR analyses suggested that the serotype a and c polysaccharides carried approximately one acetyl group per two sugar residues, although the acetylated position was not identified. In quantitative precipitin inhibition tests, the component sugars showed very low inhibition, whereas the partial hydrolysates of these antigens were effective inhibitors. These results suggest that the serotype-specific antisera recognize larger oligosaccharide units.

Aggregatibacter actinomycetemcomitans↗
PubMed1975

Staphylococcal micrococcins. II. Isolation, purification and identification.

Seven strains belonging to the Micrococcaceae family and excreting substances with antibiotic activity, were grown in submerged cultures on technical scale for isolation, purification and identification of biologically active compounds. Two basic substances were isolated and classified to the micrococcin antibiotics family. The naturally occurring mixture of micrococcin M1 and M3 was called micrococcin M. This antibiotic has the formula C48H50O11N12S6 and a molecular weight of about 1160, melting point 221--224 degrees C, and optical rotation [a]20/D = + 66.6. Other antibiotically active substances produced by seven investigated strains were identified as micrococcin M or as separate compounds. Comparison with previously described micrococcin and micrococcin P has been made.

Anti-Bacterial Agents↗
PubMed1986

[Experimental and theoretical conformation analysis of the O-antigenic polysaccharide from Pseudomonas cepacia strain 3181. I. Disaccharide links].

Nuclear Overhauser effects, with preirradiation of glycoside bond anomeric protons, coupling constants 3J C3, H1' and 3J C1', H4 and linkage optical rotations A were measured for L-Rha beta 1-3-L-Rha alpha 1-OMe and L-Rha alpha 1-3-L-Rha alpha 1-OMe which are the models of the disaccharide units of the Pseudomonas cepacia polysaccharide. Theoretical conformational analysis was carried out in terms of a mechanical molecular model approximation. The spatial structures of these disaccharides as well as of D-Rha alpha 1-2-D-Rha beta 1-OMe in aqueous solutions were discussed basing on the obtained results.

Antigens, Bacterial↗
PubMed1988

[Antigenic polysaccharides of bacteria. 32. The structure of O-specific polysaccharide chains of Pseudomonas cepacia serotype B and E lipopolysaccharides containing D-fucose].

On the basis of acid hydrolysis, methylation, 1H and 13C NMR analysis, and calculation of specific optical rotation, the following structures were established for O-specific polysaccharides of Pseudomonas cepacia serotypes B and E: ----3)-beta-D-Galf-(1----3)-alpha-D-Fucp-(1----serotype B ----3)-beta-D-GlcpNAc-(1----3)-alpha-D-Fucp-(1----serotype E A characteristic feature of the polysaccharides is the presence of D-fucose, rather rare for bacterial antigens.

Antigens, Bacterial↗
PubMed1988

[Antigenic polysaccharides of bacteria. 33. The structure of O-specific polysaccharide chain of lipopolysaccharide from Pseudomonas cepacia serotype 6].

On mild acid degradation of the Pseudomonas cepacia serotype 6 lipopolysaccharide, the O-specific polysaccharide was obtained, which contains D-mannose and D-galactose residues in the ratio approximately 1:1, as well as O-acetyl groups. On the basis of 1H and 13C NMR analysis, calculation of specific optical rotation, and methylation, it was concluded that the polysaccharide possesses the following structure: (formula; see text) Regularities in glycosidation effects in 13C NMR spectra of 1,3-linked disaccharides containing furanoside residues are discussed.

Antigens, Bacterial↗
PubMed1989

Hemodynamic and electrophysiologic effects of disopyramide enantiomers in a canine blood superfusion model.

The use of disopyramide is often limited because of adverse hemodynamic or electrophysiologic side effects. We compared the S(+) and R(-) enantiomers of disopyramide to the clinically used racemic mixture in a canine blood superfusion model. Eighteen support animals (group I) provided extracorporeal blood superfusion of isolated canine cardiac Purkinje fibers. Following administration of 2 mg/kg disopyramide intravenously (i.v.) [S(+), R(-), or racemic] hemodynamic and electrocardiographic parameters were temporally assessed in the support animals while simultaneous cellular electrophysiologic effects were recorded from the blood-superfused Purkinje fibers. An additional 13 animals (group II) underwent extended hemodynamic and pharmacokinetic analysis without the external atrioventricular (AV) shunt required for blood superfusion. Mean peak serum concentrations of racemic disopyramide and its enantiomers were similar (2.7 to 3.1 mg/L), but clearance was stereo-specific [half-life (t1/2) of 1.99 h for S(+) vs. 2.79 h for R(-) disopyramide]. Left ventricular (LV) function was impaired following drug administration, irrespective of optical rotation (cardiac output decreased by 20.8%, LV dP/dtmax decreased by 22.4%). Depression of phase 0 Vmax of the Purkinje fiber action potential was also nonstereo-dependent. S(+) disopyramide prolonged the QTC interval by 11.5% and increased terminal action potential duration (APD75) and effective refractory period (ERP) by 21.2 and 19.0%, respectively. R(-) disopyramide slightly increased the QTC interval (+2.3%) but decreased APD75 and ERP by 8.9 and 6.8%, respectively. The effect of racemic disopyramide on repolarization indexes was intermediate to that of its enantiomers. These data support nonstereodependent depression of both myocardial contractility and sodium channel conductance by disopyramide. Changes in APD and refractoriness were dependent on stereochemical configuration.

Animals↗
PubMed1988

[Antigenic polysaccharides of bacteria. 34. Structure of O-specific polysaccharide chains of lipopolysaccharides from Pseudomonas cepacia strains IMV 4207 (Serotype A) and IMV 598/2].

On the basis of non-destructive analysis by means of 1H and 13C NMR spectroscopy and calculation of specific optical rotation, it was concluded that O-specific polysaccharide of Pseudomonas cepacia strain IMV 4207 (serotype A) has the structure (I): (formula; see text) Two structurally different polysaccharides were found in the ratio of approximately 2.5:1 in P. cepacia strain IMV 598/2 which is serologically related to serotype A in Nakamura classification and serotype 2 in Heidt classification. The minor polysaccharide has the structure (I) whereas the major one possesses the structure (II) which is characteristic of the formerly studied O-specific polysaccharide of P. cepacia strain IMV 4137 belonging to serotype 2: ----4)-beta-D-Galp-(1----2)-alpha-L-Rhap-(1----.

Antigens, Bacterial↗
PubMed1989

[Structure of an O-specific polysaccharide of Proteus mirabilis 03, containing N-(2-hydroxyethyl)-D-alanine].

O-Specific polysaccharide, obtained by mild acid degradation of the Proteus mirabilis 03 lipopolysaccharide, was dephosphorylated with 48% HF to give a linear polysaccharide and an amino acid, N-(2-hydroxyethyl)-D-alanine. The structure of the polysaccharide was determined by methylation, the Smith degradation and computer-assisted analysis of the 13C NMR spectra of original and dephosphorylated polymers and oligomers. The structure of the amino acid was elucidated by using 1H and 13C NMR spectroscopy and mass spectrometry (applied to the acetylated methyl ester derivative), optical rotation and CD spectrum data and comparison with the synthetic sample. The repeating unit of P. mirabilis 03 O-specific polysaccharide is shown to have the following structure: (formula; see text)

Alanine↗
PubMed1989

The structure and serologic distribution of an extracellular neutral polysaccharide from Pseudomonas aeruginosa immunotype 3.

Previous work has described small molecular weight neutral polysaccharides from isolates of Pseudomonas aeruginosa that appear to be associated with the lipopolysaccharide (LPS) and distributed across serologic barriers defined by antibody to the O side chain. We have isolated and characterized another of these structures obtained from culture supernatants of an immunotype 3 strain of P. aeruginosa. The isolated neutral polysaccharide has a tetrasaccharide repeat unit: (formula; see text) where Rha is rhamnose. The structure was determined by 1H and 13C nuclear magnetic resonance spectroscopy including nuclear Overhauser enhancement experiments, acid hydrolysis, methylation analysis, Smith degradation, and optical rotation determinations. Polyclonal antibodies raised to intact and alkali-treated (0.1 N NaOH, 56 degrees C, 2 h) LPS from the seven Fisher immunotype strains of P. aeruginosa bound well to the neutral polysaccharide. Antibodies affinity purified from these sera using immobilized neutral polysaccharide as well as a neutral polysaccharide-specific monoclonal antibody, E87, reacted with an antigenically similar structure found among many isolates of different LPS serotypes in a colony blot and with LPS from the seven Fisher immunotypes in an immunoblot. In an immunoblot assay, the neutral polysaccharide inhibited binding of the monoclonal antibody, E87, to material present in LPS preparations from a variety of serotypes. This structure may represent another P. aeruginosa neutral polysaccharide variant found associated with the LPS.

Carbohydrate Conformation↗
PubMed1989

[Cholecalciferol Reference Standard (Control 871) of National Institute of Hygienic Sciences].

Cholecalciferol Reference Standard (Control 871) for the Japanese Pharmacopoeia was prepared. The following analytical data were obtained: melting point, 86.3 degrees C; infrared spectrum, same as the Japanese Pharmacopoeia Standard "Cholecalciferol Standard (Control 851)"; absorbance, E1%1cm (265 nm) = 474.5; optical rotation, [alpha]20D = + 110.0 degrees; thinlayer chromatography, same as the Japanese Pharmacopoeia Standard; highperformance liquid chromatography, contaminants were not detected; assay, 100.7%. On the basis of those results, this material was authorized as the Japanese Pharmacopoeia Standard (control 871).

Chemical Phenomena↗
PubMed1989

[Ergocalciferol Reference Standard (Control 871) of National Institute of Hygienic Sciences].

The Ergocalciferol Reference Standard (Control 871) for the Japanese Pharmacopoeia was prepared. The following analytical data were obtained: melting point, 115.9 degrees C; infrared spectrum, same as the Japanese Pharmacopoeia Standard "Ergocalciferol Standard (Control 851)"; absorbance, E1%1cm (265 nm) = 464.8; optical rotation, [alpha]20D = +104.7 degrees; thin-layer chromatography, same as the Japanese Pharmacopoeia Standard; high-performance liquid chromatography, contaminants were not detected; assay, 101.2%. On the basis of those results, this material was authorized as the Japanese Pharmacopoeia Standard (control 871).

Chemical Phenomena↗
PubMed1989

[Diflucortolone-21-valerate Reference Standard (Control 871) of National Institute of Hygienic Sciences].

Diflucortolone-21-valerate was tested for the preparation of "Diflucortolone-21-valerate Reference Standard (Control 871)". Analytical data obtained were as follows: loss on drying, 0.05%; infrared spectrum, 1745, 1727, 1667, 1625, 1611, 1169 cm-1; ultraviolet spectrum, lambda max = 239 nm; absorbance, E1%1cm (239 nm) = 348.8; optical rotation, [alpha]20D: + 100.8 degrees; melting point, 203.2 degrees C; thin-layer chromatography, three contaminants were detected; high-performance liquid chromatography, two contaminants were detected; fluorine, 8.06%. On the basis of those results, this material was authorized as the National Institute of Hygienic Sciences Reference Standard (Control 871).

Chemical Phenomena↗
PubMed1989

[Prednisolone Reference Standard of National Institute of Hygienic Sciences].

Prednisolone reference standard for the Japanese Pharmacopoeia was prepared. The quality of raw material was examined and compared with the previous reference standard (Control 821). Analytical data for this substance were as follows: loss on drying, 0.04%; melting point, 234.1 degrees C (decomposition); optical rotation, [alpha] 20D + 100.2 degrees; UV spectrum, lambda max = 243 nm; absorptivity, E1%1cm (243 nm) = 415; IR spectrum, 1711, 1655, 1612, 1111, 899 cm-1; one impurity was detected by TLC and high-performance liquid chromatography (HPLC), respectively; assay by HPLC, 100.1%. Based on the above results, this raw material was authorized as the Reference Standard of National Institute of Hygienic Sciences.

Chemical Phenomena↗
PubMed1989

Structural heterogeneity among unique sulfated L-galactans from different species of ascidians (tunicates).

The sulfated polysaccharides that occur in the tunic of ascidians differ markedly in molecular weight and chemical composition. A high molecular weight fraction (F-1), which has a high galactose content and a strong negative optical rotation, is present in all species. Several structural differences were observed among the F-1 fractions obtained from three species of ascidians that were studied in detail. Large numbers of alpha-L-galactopyranose residues sulfated at position 3 and linked glycosidically through position 1----4 are present in F-1 from all three ascidians. However, alpha-L-galactopyranose units, 1----3-linked and partially sulfated at position 4, comprise about half of the sugar units in the central core of F-1 from Ascidian nigra. In addition, L-galactopyranose nonreducing end units occur in F-1 from Styela plicata and A. nigra, but comprise only a minor fraction of F-1 from Clavelina sp. The combination of these various component units gives a complex structure for F-1 from S. plicata and A. nigra, whereas F-1 from Clavelina sp. possesses a simpler structure. The structures of these ascidian glycans are unique among all previously described sulfated polysaccharides, since they are highly branched (except that from Clavelina sp), sulfated at position 3, and contain large amounts of L-galactose without its D-enantiomorph. These data show unusual examples of polyanionic glycans with structural function in animal tissues.

Animals↗
PubMedDate not supplied

Production and isolation of aflatoxin M1 for toxicological studies.

One hundred mg aflatoxin M1 was produced and purified for toxicological studies. Aspergillus flavus NRRL 3251 was cultured on rice to produce aflatoxins B1, B2, M1, and M2, B1 and B2 were separated from M1 and M2 by a normal phase low pressure liquid chromatography (LC) column. M1 was then separated from M2 by a reverse phase low pressure LC column. Recoveries of aflatoxins from the LC columns were about 90%. The purified M1 was confirmed by ultraviolet-visible spectrometry, mass spectrometry, nuclear magnetic resonance spectrometry, optical rotation, and its mutagenicity to Salmonella typhimurium TA98.

Aflatoxin M1↗
PubMedDate not supplied

[Isoelectric fractions of healthy human serum albumin and their ability to bind bilirubin].

The article deals with the isoelectric spectrum of human serum albumin isolated by electrophoresis in polyacrylamide gel, on agar-agar, by salting out with ammonium sulphate and also by the Cohn method. It is shown that the way of albumin isolation, except the Cohn method, does not affect the quantitative and qualitative characteristics of its isoelectric spectrum obtained on ampholines by focusing. Fractions isolated from healthy people have always pI 4.7, 5.1, 5.5, their ratio being different. Albumin and its fractions are identical immunochemically. Dispersion of the fraction content optic rotation, except the fraction with pI 5,1, is the same as in initial albumin. Bilirubin is bound mainly (80%) by the fraction with pI 4.7 and it is absent in the fraction with pI 5.5.

Bilirubin↗