1H NMR studies of [N-MeAib1, Tyr(Me)4]ANGII and [N-MeAib1, Tyr(Me)4, Ile8]ANGII in dimethylsulfoxide by nuclear Overhauser effect (NOE) enhancement spectroscopy: cis-trans Isomerism of the His-Pro bond

1990 ◽  
Vol 55 (4) ◽  
pp. 1106-1111 ◽  
Author(s):  
John Matsoukas ◽  
Paul Cordopatis ◽  
Raghav Yamdagni ◽  
Graham J. Moore
Keyword(s):  
1H Nmr ◽  
Nuclear Overhauser Effect ◽  
Nmr Studies ◽  
Restricted Rotation ◽  
Overhauser Effect ◽  
Major Isomer ◽  
Conformational Properties ◽  
Nuclear Overhauser

The conformational properties of the Sarmesin analogues [N-MeAib1, Tyr(Me)4]ANGII and [N-MeAib1, Tyr(Me)4, Ile8]ANGII in hexadeutero-dimethysulfoxide were investigated by Nuclear Overhauser Effect (NOE) Enhancement Studies. Cis-trans isomers (ratio 1 : 6) due to restricted rotation of the His-Pro bond were observed. Interresidue interactions between the His Cα proton and the two Pro Cδ protons revealed that the major isomer was the trans.

scholarly journals Proton NMR studies on the covalently linked RNA-DNA hybrid r(GCG)d(TATACGO). Assignment of proton resonances by application of the nuclear Overhauser effect

1983 ◽  
Vol 11 (16) ◽  
pp. 5717-5738 ◽  
Author(s):  
J.-R. Mellema ◽  
C.A.G. Haasnoot ◽  
G.A. van der Marel ◽  
G. Wille ◽  
C.A.A. van Boeckel ◽  
...  
Keyword(s):  
Nuclear Overhauser Effect ◽  
Proton Nmr ◽  
Nmr Studies ◽  
Overhauser Effect ◽  
Proton Resonances ◽  
Covalently Linked ◽  
Nuclear Overhauser

Preparation, characterization, and antioxidant properties of polystyrenes with 4-methoxyphenol end groups

1983 ◽  
Vol 61 (1) ◽  
pp. 124-127 ◽  
Author(s):  
Brian K. Hunter ◽  
Kenneth E. Russell ◽  
Ataa K. Zaghloul
Keyword(s):  
Molecular Weight ◽  
Nuclear Overhauser Effect ◽  
Average Molecular Weight ◽  
Antioxidant Properties ◽  
Low Molecular Weight ◽  
Nmr Studies ◽  
Overhauser Effect ◽  
End Groups ◽  
Nuclear Overhauser ◽  
C Nmr

Polystyrenes with 4-methoxyphenol end groups have been prepared by the cationic polymerization of styrene in the presence of the phenol. The products range from 1:1 adduct to polymer of number-average molecular weight close to 3000. The 1:1 adduct separated from the reaction mixture was shown by nuclear Overhauser effect studies to be 2-(1-methylbenzyl)-4-methoxyphenol. Only about half of the polymer molecules have 4-methoxyphenol end groups. 13C nmr studies indicate that the polystyrene chains are attached principally at the 2-position of the phenol. The activity of the polymer as an antioxidant is comparable to that of corresponding low molecular weight methoxyphenols including butylated hydroxyanisole.

Conformational studies of Angiotensin II and analogues in dimethyl sulfoxide by 1H NMR: Lability and intramolecular interactions of the tyrosine hydroxyl and histidine imidazole NH protons

1991 ◽  
Vol 56 (6) ◽  
pp. 1348-1357 ◽  
Author(s):  
John Matsoukas ◽  
Glen Bigam ◽  
Raghav Yamdagni ◽  
Graham J. Moore
Keyword(s):  
Dimethyl Sulfoxide ◽  
Nuclear Overhauser Effect ◽  
Peptide Bond ◽  
Intramolecular Interactions ◽  
Nmr Studies ◽  
Hydroxyl Proton ◽  
H Nmr ◽  
Overhauser Effect ◽  
Nuclear Overhauser ◽  
Deshielding Effect

1H NMR studies in dimethyl sulfoxide illustrate that the tyrosine hydroxyl proton and the histidine imidazole NH proton in [Sar1]ANGII and analogues are labile at neutral pH but not at acid pH. This is attributable to intramolecular interactions of these groups with negatively charged groups. Methylation or elimination of the Tyr hydroxyl in [Sar1]ANGII and analogues, invokes a small but consistent deshielding effect on the His C-2 and C-4 protons, suggesting an interaction between the Tyr hydroxyl and the His ring. Nuclear Overhauser Effect (NOE) enhancement experiments in {Sar1]ANGII and the Sarmesin analogue [Des1, Tyr(Me)4]ANGII, support the Tyr/His interaction and confirm the presence of a trans His-Pro peptide bond.

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