NMR studies of low-spin ferric complexes of natural porphyrin derivatives. 2. Determination of the dimer structure of the biscyano complex using intermolecular paramagnetic dipolar relaxations

1978 ◽  
Vol 100 (26) ◽  
pp. 8092-8096 ◽  
Author(s):  
David B. Viscio ◽  
Gerd N. La Mar
Keyword(s):  
Nmr Studies ◽  
Dimer Structure ◽  
Porphyrin Derivatives

Synthesis and characterization of 19F NMR chelators for measurement of cytosolic free Ca

1987 ◽  
Vol 252 (4) ◽  
pp. C441-C449 ◽  
Author(s):  
L. A. Levy ◽  
E. Murphy ◽  
R. E. London
Keyword(s):  
Chemical Shifts ◽  
Cell Types ◽  
Free Calcium ◽  
Tetraacetic Acid ◽  
Nmr Studies ◽  
Cytosolic Free Calcium ◽  
Fluorine Nmr ◽  
Dissociation Constant Kd

Fluorine 19 nuclear magnetic resonance (NMR) studies of intracellular fluorinated calcium chelators provide a useful strategy for the determination of cytosolic free calcium levels in cells and perfused organs. However, the fluorinated chelator with the highest affinity for calcium ions which has been described to date. 1,2-bis-(2-amino-5-fluorophenoxy)ethane-N,N,N',N'-tetraacetic acid (5FBAPTA), exhibits a dissociation constant (Kd) value 5- to 10-fold greater than the intracellular calcium concentration levels in most cell types, thus limiting the ability of fluorine NMR to report these concentrations reliably. We have consequently designed and synthesized several fluorinated calcium chelators with higher affinity for calcium. The best of these, 2-(2-amino-4-methyl-5-fluorophenoxy)-methyl-8 aminoquinidine-N,N,N',N'-tetraacetic acid (quinMF), has a Kd value approximately 10 times lower than that of 5FBAPTA. Several of the newly synthesized indicators have different chemical shifts for the calcium complexed and uncomplexed chelators to allow the simultaneous use of two indicators. In addition to providing information about the level of cytosolic free calcium, chelators containing a quinoline ring exhibit considerable sensitivity to magnesium levels and hence have potential application for the determination of cytosolic-magnesium concentrations. Application of these chelators is illustrated by determination of the cytosolic-free calcium level in erythrocytes. Use of quinMF, the chelator with the lowest Kd value, gives a calcium value of 25-30 nM.

ChemInform Abstract: NMR STUDIES OF LOW-SPIN FERRIC COMPLEXES OF NATURAL PORPHYRIN DERIVATIVES. 1. FFECT OF PERIPHERAL SUBSTITUENTS ON THE Π ELECTRONIC ASYMMETRY N BISCYANO COMPLEXES

1979 ◽  
Vol 10 (12) ◽  
Author(s):  
G. N. LA MAR ◽  
D. B. VISCIO ◽  
K. M. SMITH ◽  
W. S. CAUGHEY ◽  
M. L. SMITH
Keyword(s):  
Nmr Studies ◽  
Porphyrin Derivatives

High-resolution proton NMR studies of gangliosides. 1. Use of homonuclear two-dimensional spin-echo J-correlated spectroscopy for determination of residue composition and anomeric configurations

Biochemistry ◽  
1983 ◽  
Vol 22 (11) ◽  
pp. 2676-2687 ◽  
Author(s):  
Theodore A. W. Koerner ◽  
James H. Prestegard ◽  
Peter C. Demou ◽  
Robert K. Yu
Keyword(s):  
High Resolution ◽  
Spin Echo ◽  
Proton Nmr ◽  
Two Dimensional ◽  
Nmr Studies ◽  
Residue Composition

scholarly journals Determination of the Binding Situation of Pyridine in Xylan Sulfates by Means of Detailed NMR Studies

2019 ◽  
Vol 221 (1) ◽  
pp. 1900327 ◽  
Author(s):  
Lars Gabriel ◽  
Wolfgang Günther ◽  
Friederike Pielenz ◽  
Thomas Heinze
Keyword(s):  
Nmr Studies

Structural determination of the group K capsular polysaccharide of Neisseriameningitidis: a 2D-NMR analysis

1985 ◽  
Vol 63 (10) ◽  
pp. 2781-2786 ◽  
Author(s):  
Francis Michon ◽  
Jean Robert Brisson ◽  
René Roy ◽  
Harold J. Jennings ◽  
Fraser E. Ashton
Keyword(s):  
Capsular Polysaccharide ◽  
2D Nmr ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Electronic Effects ◽  
Nmr Studies ◽  
Polysaccharide Antigen ◽  
One Dimensional ◽  
The One

The capsular polysaccharide antigen of Neisseriameningitidis group K was isolated by Cetavlon precipitation and purified by ion-exchange chromatography. The structure of the K polysaccharide was determined to a large extent by comprehensive proton and carbon-13 nuclear magnetic resonance (nmr) studies. In these studies one-dimensional and two-dimensional experiments were carried out directly on the K polysaccharide. The K polysaccharide is composed of the following repeating unit: -4)β-D-ManpNAcA(1→3) [4-OAc]β-D-ManpNAcA(1→. Except for the one-bond couplings between their anomeric carbons and protons [Formula: see text], all the nmr spectroscopic evidence was consistent with both 2-acetamido-2-deoxy-D-mannopyranosyluronic acid residues adopting the 4C1 (D) conformation and having the β-D-configuration. This ambiguity in [Formula: see text] is probably due to through-space electronic effects generated by the presence of contiguous carboxylated sugar residues in the K polysaccharide. The O-acetyl substituents of the K polysaccharide are essential for its antigenicity to group K polysaccharide-specific antibodies.

NMR studies in the heterocyclic series. 27—Carbon-13 NMR determination of the protonation site of aminopyrazoles in trifluoroacetic acid

1985 ◽  
Vol 23 (5) ◽  
pp. 367-374 ◽  
Author(s):  
Marta Bruix ◽  
Javier De Mendoza ◽  
Rosa Maria Claramunt ◽  
José Elguero
Keyword(s):  
Trifluoroacetic Acid ◽  
Nmr Studies ◽  
Protonation Site ◽  
Heterocyclic Series
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