Potentiometric and NMR studies on palladium(II) complexes of oligoglycines and related ligands with non-co-ordinating side chains

1999 ◽  
pp. 3295-3302 ◽  
Author(s):  
Csaba Gábor Ágoston ◽  
Teresa Kowalik Jankowska ◽  
Imre Sóvágó
Keyword(s):  
Side Chains ◽  
Nmr Studies

Chemical and 13C NMR Studies of a Rhamnoarabinogalactan from the Leaves of Plantago lanceolata L. var. libor

1994 ◽  
Vol 59 (12) ◽  
pp. 2714-2720 ◽  
Author(s):  
Alžbeta Kardošová ◽  
Peter Capek
Keyword(s):  
Nmr Spectroscopy ◽  
13C Nmr ◽  
Plantago Lanceolata ◽  
Partial Hydrolysis ◽  
Side Chains ◽  
Methylation Analysis ◽  
Nmr Studies ◽  
C Nmr

A rhamnoarabinogalactan isolated from the leaves of Plantago lanceolata L. var. libor has been investigated by methylation analysis, partial hydrolysis, and 13C NMR spectroscopy. The structural conclusions obtained by 13C NMR measurements were consistent with the data from methylation analysis. The polysaccharide has a β-(1→6)-D-galactan core branched on O-3 by side chains of (1→5)-linked α-L-arabinofuranosyl units, some of which bear in position O-5 terminal β-D-galactopyranosyl residues. L-Rhamnose occurs as nonreducing ends.

Further Novel 6,7-Dimethoxy-8-Prenylated Coumarins from the Aerial Parts of Phebalium elatius ssp. becklevi

1990 ◽  
Vol 45 (9-10) ◽  
pp. 927-930 ◽  
Author(s):  
Jamila A. El-Turbi ◽  
James A. Alexander ◽  
Alexander I. Gray ◽  
Peter G. Waterman
Keyword(s):  
Side Chains ◽  
Nmr Studies ◽  
Aerial Parts ◽  
Methyl Butanoate

Abstract From the aerial parts of Phebalium elatius ssp. beckleri six novel coumarins have been isolat­ ed. These com pounds are all based on a 6,7-dimethoxycoumarin nucleus with a modified C-8 isoprenyl substituent. The prenyl side chains were identified, primarily on the basis of NMR studies, as 1,2-epoxy-3-methylbut-3-enyl = (+)-6 -methoxyphebalosin (1), 1-acetoxymethyl-2-methylprop-2-enyl = (+)-6 -m ethoxyisomurralonginol acetate (2), 1,2-epoxy-3-hydroxy-4-(3-m ethylbutanoyloxy)-3-m ethylbutanyl = 1 ′,2′-epoxy-6-methoxycasegravol-4′-(3-methyl)-butanoate (3), 1-(S)-hydroxy-3-methyl-2-oxobutanyl = (+)-6 -methoxymurranganon (4), 3-methyl-2-oxotetrahydrofuran-4-yl = 6-methoxy-3′.4′-dihydroisomicrominutin (5) and (E)-3-hydroxy-3-methylbut-l-enyl = 6 -methoxymurraol (6).

Orientational Order of α-Helical Poly (γ-Benzyl L-Glutamate) in the Lyotrao-Phiecl Ilciaqlu Idp Oclryy(yS-Tbaelnlziynle Ls-Tate and Conformation of the Pendant Side Chain

1988 ◽  
Vol 134 ◽  
Author(s):  
Akihiro Abe ◽  
Toshimasa Yamazaki
Keyword(s):  
Crystalline State ◽  
Liquid Crystalline ◽  
Orientational Order ◽  
Equilibrium Concentration ◽  
Side Chain ◽  
Side Chains ◽  
Nmr Studies ◽  
Rotational Isomeric State ◽  
System A ◽  
Acid Esters

ABSTRACTDeuterium NMR studies have been performed on variously labeled PBLG samples in the lyotroplc liquid crystalline state. The orientational orders S of the a-helical backbone were estimated from the observed quadrupolar splittings ∆v of the N-D and Cα-D bond. The values of S decrease gradually by dilution until the upper equilibrium concentration (B-point) is reached. The concentration dependence of Scrit has been compared with those derived from standard theories. The relatlve orientation of side chains with respect to the backbone was elucidated by the rotational isomeric state analysis of the ∆v/S data observed for the γ-, γ-, and ζ-methylene, and p-benzyl deuterons. The results indicate that the steric overlaps between adjacent side chains play an important role in determining the preference of conformations in the PBLG system. A similar analysis has been extended to poly(L-glutamic acid) esters carrying a homologous series of ester residues, -C(O)O(CH2)nC6D5 with n = 2 and 3. A distinct odd-even oscillation was observed for the orientation of the terminal phenyl groups with n.

Interaction between Spin Labels and DPPC Vesicles

1986 ◽  
Vol 41 (7-8) ◽  
pp. 799-801
Author(s):  
W. Lohmann ◽  
B. Kiefer ◽  
W. Schmehl
Keyword(s):  
Spin Label ◽  
High Field ◽  
Spin Labels ◽  
Side Chains ◽  
Nmr Studies ◽  
H Nmr ◽  
Low Field ◽  
Head Groups ◽  
Vesicle Preparation ◽  
Stabilizing Effect

Abstract1H NMR studies on DPPC vesicles labeled with the spin labels (1,14) or (12,3) have shown that both of the spin labels influence the fatty acid side chains as well as the choline head groups. The spin label (12,3) affects, natural­ly, the head groups stronger than the spin label (1,14), while the reversed effect can be observed at the side chains. This effect progresses with time after vesicle preparation and is fully developed after about 24 h. Addition of Na- ascorbate, at this time, seems to reverse the effect indicat­ing a stabilizing effect of the vitamin on the membrane. These results could be confirmed by ESR investigations according to which the high-field signal seems to be indica­tive for changes occurring at the side chains, while the low-field signal seems to reflect modifications of the head groups. Since the spin label (1,14) affects considerably the head groups at temperatures <6 °C, in which case the spec­trum is very similar to that obtained with spin label (12,3) at 24 °C, one might conclude that there might be a phase transition in regard to the head groups.

scholarly journals Dynamics of the three methionyl side chains of Streptomyces subtilisin inhibitor. Deuterium NMR studies in solution and in the solid state

1996 ◽  
Vol 5 (1) ◽  
pp. 127-139 ◽  
Author(s):  
Atsuo Tamura ◽  
Michio Matsushita ◽  
Akira Naito ◽  
Shuichi Kojima ◽  
Kin-Ichiro Miura ◽  
...  
Keyword(s):  
Solid State ◽  
Deuterium Nmr ◽  
Side Chains ◽  
Nmr Studies ◽  
Subtilisin Inhibitor

Structural properties of D-mannopyranosyl rings containing O-acetyl side-chains

2019 ◽  
Vol 75 (8) ◽  
pp. 1166-1174 ◽  
Author(s):  
Toby Turney ◽  
Wenhui Zhang ◽  
Allen G. Oliver ◽  
Anthony S. Serianni
Keyword(s):  
Density Functional ◽  
Side Chain ◽  
Side Chains ◽  
Nmr Studies ◽  
Functional Theory ◽  
Torsion Angles ◽  
Bond Lengths ◽  
Side Chain Conformation ◽  
Chain Conformations ◽  
Good Agreement

The crystal structures of 1,2,3,4,6-penta-O-acetyl-α-D-mannopyranose, C16H22O11, and 2,3,4,6-tetra-O-acetyl-α-D-mannopyranosyl-(1→2)-3,4,6-tri-O-acetyl-α-D-mannopyranosyl-(1→3)-1,2,4,6-tetra-O-acetyl-α-D-mannopyranose, C40H54O27, were determined and compared to those of methyl 2,3,4,6-tetra-O-acetyl-α-D-mannopyranoside, methyl α-D-mannopyranoside and methyl α-D-mannopyranosyl-(1→2)-α-D-mannopyranoside to evaluate the effects of O-acetylation on bond lengths, bond angles and torsion angles. In general, O-acetylation exerts little effect on the exo- and endocyclic C—C and endocyclic C—O bond lengths, but the exocyclic C—O bonds involved in O-acetylation are lengthened by ∼0.02 Å. The conformation of the O-acetyl side-chains is highly conserved, with the carbonyl O atom either eclipsing the H atom attached to a 2°-alcoholic C atom or bisecting the H—C—H bond angle of a 1°-alcoholic C atom. Of the two C—O bonds that determine O-acetyl side-chain conformation, that involving the alcoholic C atom exhibits greater rotational variability than that involving the carbonyl C atom. These findings are in good agreement with recent solution NMR studies of O-acetyl side-chain conformations in saccharides. Experimental evidence was also obtained to confirm density functional theory (DFT) predictions of C—O and O—H bond-length behavior in a C—O—H fragment involved in hydrogen bonding.

Heteronuclear NMR studies of cobalamins. 11. Nitrogen-15 NMR studies of the axial nucleotide and amide side chains of cyanocobalamin and dicyanocobamides

1990 ◽  
Vol 29 (24) ◽  
pp. 4841-4844 ◽  
Author(s):  
Kenneth L. Brown ◽  
Harold B. Brooks ◽  
Xiang Zou ◽  
Mark Victor ◽  
Anjan Ray ◽  
...  
Keyword(s):  
Heteronuclear Nmr ◽  
Side Chains ◽  
Nmr Studies
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