A 13C comparative nuclear magnetic resonance study of organic solute production and excretion by the yeasts Hansenula anomala and Saccharomyces cerevisiae in saline media

1988 ◽  
Vol 34 (5) ◽  
pp. 605-612 ◽  
Author(s):  
Yves Bellinger ◽  
François Larher
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Specific Property ◽  
Glucose Consumption ◽  
Nuclear Magnetic Resonance Study ◽  
Resonance Spectroscopy ◽  
Hansenula Anomala ◽  
Organic Solute ◽  
Nuclear Magnetic

Glycerol, arabitol and trehalose were the principle solutes detected in cellular extracts of Hansenula anomala, using natural-abundance 13C nuclear magnetic resonance spectroscopy. Only the two polyols accumulated in response to increased salinity, glycerol increase being far greater. Arabitol content also increased with culture age, independently of the presence or absence of salt and in line with the evolution of trehalose content. Glycerol retention potential was 15 times greater for Hansenula than for Saccharomyces cerevisiae. The former displayed the specific property of increasing this capacity in high salt concentrations. Under such conditions its growth was associated with a limited increase in glucose consumption per unit biomass, relative to S. cerevisiae, the salt-sensitive reference yeast. In addition, a polysaccharide, the chemical nature of which was not further characterized, was detected exclusively in the external medium of Hansenula growing in the presence of salt.

A Nuclear Magnetic Resonance Study of the Metal Binding Sites in Bacitracin

1975 ◽  
Vol 53 (12) ◽  
pp. 1250-1254 ◽  
Author(s):  
Roderick E. Wasylishen ◽  
Moira R. Graham
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Metal Binding ◽  
Binding Sites ◽  
Imidazole Ring ◽  
Nuclear Magnetic Resonance Study ◽  
Resonance Spectroscopy ◽  
Metal Binding Sites ◽  
Ph Values ◽  
Nuclear Magnetic

Carbon-13 nuclear magnetic resonance spectroscopy has been used to identify sites in bacitracin which bind Cu2+ and Mn2+. Results are presented which implicate the free carboxyl groups of the aspartic and glutamic acid residues and the imidazole ring of the histidine residue as metal complexation sites between pH 6 and 8. Evidence is presented which also indicates that the thiazoline ring of bacitracin binds Mn2+. Bacitracin does not bind Cu2+ or Mn2+ at pH values of 2.5 or less.

Peptide Conformations. I. Nuclear Magnetic Resonance Study of the Carbamate Reaction of Amino Acids and Peptides

1971 ◽  
Vol 49 (5) ◽  
pp. 767-776 ◽  
Author(s):  
R. U. Lemieux ◽  
M. A. Barton
Keyword(s):  
Amino Acids ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nuclear Magnetic Resonance Study ◽  
Amide Bond ◽  
Resonance Spectroscopy ◽  
Peptide Conformations ◽  
End Distance ◽  
Phenylalanine Residue ◽  
Nuclear Magnetic

Nuclear magnetic resonance spectroscopy has been applied to the study of carbamate formation in solutions of amino acids and peptides in a carbonate-bicarbonate system. The possible conformations of these carbamates are discussed in terms of the n.m.r. data obtained. The n.m.r. parameters are reported for the diastereomers L-alanyl-L or D-phenylalanine and L-phenylalanyl-L or D-alanine and for the dipeptide glycyl-L-phenylalanine and their carbamates. The results are interpreted in terms of preferred rotamers about the Cα—Cβ bond of the phenylalanine residue and a β-type conformation of the peptide chain, wherein the two α-protons lie in the plane of the amide bond. All observations are in agreement with a shorter end to end distance in L,D- compared with L,L-dipeptides.

A 13C nuclear magnetic resonance study of selectivity in the binding of univalent counterions by heparin

1988 ◽  
Vol 66 (10) ◽  
pp. 2601-2604 ◽  
Author(s):  
Photis Dais ◽  
Kevin R. Holme ◽  
Arthur S. Perlin
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nuclear Magnetic Resonance Study ◽  
Resonance Spectroscopy ◽  
Free Energies ◽  
Binding Selectivity ◽  
Hydrated Ions ◽  
Binding Preference ◽  
13C Nuclear Magnetic Resonance ◽  
Nuclear Magnetic

The binding selectivities of univalent counterions for heparin in the systems Ca2+/M+/HEP, where M+ = Li+, Na+, K+, Cs+, TMA+, have been studied by 13C nuclear magnetic resonance spectroscopy. Chemical shift displacements of the various 13C nuclei of heparin in these systems clearly indicate that the binding selectivity of the polymer for univalent counterions increases with an increase in the radius of the hydrated cation form, namely Li+ > Na+ > K+ > Cs+ > TMA+. An explanation for this binding preference is offered on the basis of electrostatic and entropic terms, whereby the latter is reflected in changes in the hydration volumes of the univalent cations. Differences in the magnitude of these hydration volumes, in relation to the free energies of hydration, may account for a binding selectivity that favours the more highly hydrated ions.

The Properties Of Phosphorus In Polycrystalline Silicon - A Nuclear Magnetic Resonance Study

1986 ◽  
Vol 71 ◽  
Author(s):  
Michael J. Mccarthy ◽  
B. Meyerson ◽  
M. S. Karim ◽  
J. A. Reimer
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Grain Boundary ◽  
Polycrystalline Silicon ◽  
Chemical Vapor ◽  
Boundary Region ◽  
Nuclear Magnetic Resonance Study ◽  
Resonance Spectroscopy ◽  
Phosphorus Segregation ◽  
Nuclear Magnetic

AbstractPhosphorus segregation at grain boundaries in thin film polycrystalline silicon has been investigated by nuclear magnetic resonance spectroscopy. Amorphous silicon thin frims were deposited by plasma enhanced chemical vapor deposition with 1% phosphine in silane. The films were subsequently annealed at 700°C and 800°C to produce a fine grained polycrystalline material. All of the phosphorus atoms were found to be four-fold coordinated at the grain boundary. The P atoms were found to have three different environments in the grain boundary region. These results will be discussed in relationship to the carrier trapping and dopant segregation models.

Complexes of vanadium(V) with α-hydroxycarboxylic acids studied by 1H, 13C, and 51V nuclear magnetic resonance spectroscopy

1987 ◽  
Vol 65 (10) ◽  
pp. 2434-2440 ◽  
Author(s):  
M. Madalena Caldeira ◽  
M. Luísa Ramos ◽  
Nuno C. Oliveira ◽  
Victor M. S. Gil
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Relative Stability ◽  
Nuclear Magnetic Resonance Study ◽  
Resonance Spectroscopy ◽  
Magnetic Resonance Study ◽  
Hydroxycarboxylic Acids ◽  
Ph Range ◽  
Nuclear Magnetic

A proton, carbon-13, and vanadium-51 nuclear magnetic resonance study is reported on the number, stoichiometry, geometry, and relative stability of the complexes that form when vanadate(V) solutions are mixed with each one of the following organic α-hydroxyacids in the pH range ~2.5 – ~7: glycolic, lactic, chloro-3- and phenyl-3-lactic, mandelic, glyceric, and malic acids. The predominant complexes have 1:1 composition (almost certainly in a polymeric structure) in contrast with the 1:2 (metal:ligand) stoichiometry of the corresponding Mo(VI) and W(VI) complexes.

Nuclear magnetic resonance study of addition–cyclization involving ethyl thioacetoacetate and α-nucleophiles

1981 ◽  
Vol 59 (3) ◽  
pp. 629-634 ◽  
Author(s):  
Michael Cocivera ◽  
Soumen Basu ◽  
Leslie Copp ◽  
Vincenzo Malatesta
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Nuclear Magnetic Resonance Spectroscopy ◽  
Nuclear Magnetic Resonance Study ◽  
Resonance Spectroscopy ◽  
Magnetic Resonance Study ◽  
Cyclic Product ◽  
Rates Of Decay ◽  
Nuclear Magnetic

Addition of NH2NH2 or NH2OH to ethyl thioacetoacetate to form the corresponding cyclic product, 3-methylpyrazol-5-one or 3-methylisoxazol-5-one proceeds via cyclization of the carbinolamine formed by addition to the β-keto carbon, i.e., cyclization is faster than dehydration of the carbinolamine to form the imine. In contrast the corresponding carbinolamine derived from ethylacetoacetate undergoes dehydration faster than cyclization. By means of 1H nuclear magnetic resonance spectroscopy, it is possible to detect the cyclic carbinolamine as well as another transient and measure their rates of decay. Based on these results, a mechanism is proposed.

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