|
1. |
Binding dynamics in biological systems. Interaction of MOPC‐315 with19F labelled nitrophenyl haptens |
|
Organic Magnetic Resonance,
Volume 13,
Issue 1,
1980,
Page 1-8
Dale A. Kooistra,
John H. Richards,
Stephen H. Smallcombe,
Preview
|
PDF (878KB)
|
|
摘要:
AbstractWe have studied the dynamics of binding of19F labelled haptens by mouse plasmacytoma antibody MOPC‐315, a protein which shows specificity for nitrophenyl haptens. The off‐rates for the dissociation of hapten from MOPC‐315 proteins (7S, Fab′ and Fv) were determined by the application of several methods including a technique which, in certain cases, allows the direct determination of the rate of exchange of nuclei between magnetically non‐equivalent sites without requiring prior knowledge of intrinsic line widths. Used in conjunction with independently determined data on line widths, chemical shifts, and binding affinities, these studies show that the rates for hapten association to, or dissociation from, the intact 7S antibody, the Fab′ fragment, and the Fv fragment of MOPC‐315 are essentially the same. They also indicate the presence, probably in the Fv region, of a low affinity (K∼ 103M−1) site(s) for hapten binding. The mobility of the hapten combining site decreases as the size of the protein increases. These rate data, which were determined at relatively high protein concentrations (up to 40 mg ml−1), agree with on‐rates determined at much lower protein concentrations (≤1 mg ml−1); we therefore conclude that protein aggregation, if it does occur, does not significantly affect
ISSN:0030-4921
DOI:10.1002/mrc.1270130102
出版商:John Wiley&Sons Limited
年代:1980
数据来源: WILEY
|
2. |
13C NMR chemical shifts of some highly‐branched acyclic compounds |
|
Organic Magnetic Resonance,
Volume 13,
Issue 1,
1980,
Page 9-13
Richard M. Schwarz,
Norman Rabjohn,
Preview
|
PDF (331KB)
|
|
摘要:
AbstractA study has been made of the13C chemical shifts of a number of acyclic alkanes, alkenes, nitriles and ketones which contain quaternary carbon atoms. Similar data have also been obtained for the series of compounds involved in the synthesis of triisopropylacetic acid. Substituent effects and steric factors in these highly substituted compounds are discussed in relation to the chemical shifts.
ISSN:0030-4921
DOI:10.1002/mrc.1270130103
出版商:John Wiley&Sons Limited
年代:1980
数据来源: WILEY
|
3. |
15N nuclear magnetic resonance studies of [1‐15N]nicotinamide adenine dinucleotides |
|
Organic Magnetic Resonance,
Volume 13,
Issue 1,
1980,
Page 14-16
Norman J. Oppenheimer,
Robert M. Davidson,
Preview
|
PDF (327KB)
|
|
摘要:
AbstractThe synthesis of [1‐15N]nicotinamide adenine dinucleotide is described. Chemical shift data from15N NMR studies are presented for the pyridine ring nitrogen of labeled NAD and related compounds. The results indicate a15N label in the N‐1 position to be highly sensitive to the redox‐state of the pyridine moiety, with an upfield shift of over 100 ppm observed upon reduction of NAD+to NADH. The feasibility of conducting15N NMR studies of pyridine nucleotide binding to dehydrogenases is disc
ISSN:0030-4921
DOI:10.1002/mrc.1270130104
出版商:John Wiley&Sons Limited
年代:1980
数据来源: WILEY
|
4. |
NMR spectra, MO calculations of spin–spin coupling constants and conformational analysis of substituted 1,3‐dioxolanes |
|
Organic Magnetic Resonance,
Volume 13,
Issue 1,
1980,
Page 17-25
Rois Benassi,
Luisa Schenetti,
Ferdinando Taddei,
Luigi Villa,
Vincenzo Ferri,
Preview
|
PDF (918KB)
|
|
摘要:
AbstractThe NMR spectra of a number of 2,4‐disubstituted 1,3‐dioxolanes have been recorded and the proton chemical shifts and coupling constants derived from complete spectral analysis. Vicinal coupling constants were found to be dependent on the substituent at C‐4 and this effect is more pronounced forJ(trans)of the C‐4‐C‐5 fragment. These coupling constants also indicate a homogeneous behaviour within a series with either acisortransconfiguration, although thecisbehaviour differs from that oftransisomers. This has been interpreted in terms of definite ring conformations in substituted derivatives, while the unsubstituted 1,3‐dioxolane undergoes free pesudorotation. Calculations of coupling constants were performed by semi‐empirical MO methods, both for unsubstituted 1,3‐dioxolane and for C‐4 substituted derivatives in a large number of conformations, in order to compare calculated and experimental values; the correct order ofJ(cis)andJ(trans)for 1,3‐dioxolane is obtained only by employing energies fromab‐initioMO calculations averaged over the pseudorotation circuit. For the C‐4 substituted compounds calculated coupling constants were employed in a ‘trial and error’ process for the identification of the preferred conformations of these compounds; a set of two torsional angles for each compound was derived which allows a tentative description of the geometry of each molecule. A criticism of these geometries is given according to the evidence available on the structure
ISSN:0030-4921
DOI:10.1002/mrc.1270130105
出版商:John Wiley&Sons Limited
年代:1980
数据来源: WILEY
|
5. |
Carbon‐13 NMR spectra of some tetra‐ and pentacyclic triterpene methyl ethers |
|
Organic Magnetic Resonance,
Volume 13,
Issue 1,
1980,
Page 26-27
J. W. Blunt,
M. H. G. Munro,
Preview
|
PDF (194KB)
|
|
摘要:
AbstractThe carbon‐13 NMR spectra have been recorded for representatives of three previously unexamined classes of pentacyclic triterpenes—lupanes, fernanes and arboranes. In addition to the spectra of lupeol methyl ether, cylindrin and arundoin, the spectra of a number of other triterpene methyl ethers are also recorded. The effect of methyl ether formation on the shilding values for carbons in the 3β‐hydroxy‐4,4‐dimethyl‐ ring A syste
ISSN:0030-4921
DOI:10.1002/mrc.1270130106
出版商:John Wiley&Sons Limited
年代:1980
数据来源: WILEY
|
6. |
The determination of the COOH substiuent effect for branched carboxylic acids from carbon‐13 chemical shifts |
|
Organic Magnetic Resonance,
Volume 13,
Issue 1,
1980,
Page 28-32
David H. Marr,
Preview
|
PDF (330KB)
|
|
摘要:
AbstractThe carboxyl substituent effects for branched carboxylic acids have been determined by carbon‐13 Fourier ransform nuclear magnetic resonance of eighteen measured and reported branched acids. For α‐branched systems the substituent effects are α = 15.3 ppm, β = 2.6 ppm, γ = −1.9 ppm, δ = 0.9 ppm and ϵ = 0.5 ppm. For other branched acids, the determined carboxyl substituent effects are α = 19.2 ppm, β = 2.1 ppm, γ = −1.4 ppm, δ = 0.6 ppm
ISSN:0030-4921
DOI:10.1002/mrc.1270130107
出版商:John Wiley&Sons Limited
年代:1980
数据来源: WILEY
|
7. |
Spectroscopic studies on olefins. VII–propene and 3‐methylbutene‐1; proton NMR coupling constants as a function of solvent and temperature in relation to molecular geometry |
|
Organic Magnetic Resonance,
Volume 13,
Issue 1,
1980,
Page 33-39
Frans H. A. Rummens,
Christian Simon,
Claude Coupry,
Nicole Lumbroso‐Bader,
Preview
|
PDF (702KB)
|
|
摘要:
AbstractThe proton spectra of the compounds propene (1) and 3‐methylbutene‐1 (2) have been measured in various solvents and, as neat liquids, at variable temperature. The effects of solvent and temperature on 1 are found to be small, but not negligible. The effect of temperature on the coupling constants of 2 are more pronounced, which is explained in terms of ananti‐gaucheequilibrium. To obtain a consistent ΔE° value from each temperature dependent coupling constant it is necessary to correct for the non‐conformational temperature effects (obtained from 1) as well as to correct for changes in the geometry of the entire molecule, which are concurrent with a conformational transition. Such geometry changes have been calculated by a consistent force field technique, which, when coupled with INDO‐MO calculated dependencies of coupling constants on valence (and torsional) angles, provided the changes in coupling constants. The observed temperature dependence of the coupling constants of the H2CCH— moiety of 2 could be satisfactorily explained in this fashion. The difference in energy between theantiandgaucheforms of 2 were determined as ΔE° = 1
ISSN:0030-4921
DOI:10.1002/mrc.1270130108
出版商:John Wiley&Sons Limited
年代:1980
数据来源: WILEY
|
8. |
Use of13C isotope shifts to assign carbon atoms α and β (andpara) to a hydroxy group in alkyl substituted phenols and alcohols |
|
Organic Magnetic Resonance,
Volume 13,
Issue 1,
1980,
Page 40-44
Richard A. Newmark,
James R. Hill,
Preview
|
PDF (421KB)
|
|
摘要:
AbstractDoublets can be observed for carbons α and β to the hydroxyl in aliphatic alcohols containing equimolar amounts of OH and OD dissolved in (CH3)2SO containing CaSO4desiccant. Isotopic doublets are also observed for theipsoandorthocarbons in alkyl substituted phenols.Paraisotopic doublets are observable inpara‐substituted phenols containing a large 2‐substituent. The isotope shift is positive (low field) for theparacarbon, opposite to the negative shifts usually obs
ISSN:0030-4921
DOI:10.1002/mrc.1270130109
出版商:John Wiley&Sons Limited
年代:1980
数据来源: WILEY
|
9. |
Interproton coupling constant variations in 3‐membered ring heterocycles. Separation of lone pair and inductive effects |
|
Organic Magnetic Resonance,
Volume 13,
Issue 1,
1980,
Page 45-51
Delanson R. Crist,
Arnold P. Borsetti,
Guy J. Jordan,
Charles F. Hammer,
Preview
|
PDF (715KB)
|
|
摘要:
AbstractIn order to separate inductive and lone pair effects on geminal and vicinal coupling constants in a stereochemically well‐defined system, the1H NMR spectra of phenylcyclopropane (1),N‐methyl‐2‐phenylaziridine (2), styrene oxide (3) and 1,1‐dimethyl‐2‐phenylaziridinium fluorosulfonate (4) were compared. In D2O the heterocyclic ring protons of 4 were split into an ABX pattern which gaveJ(cis)= 8.5,J(trans)= 7.4 andJ(gem)= −4.8 Hz (signs consistent with INDOR results). From the small solvent effects onJ(vic) determined from 4‐d1, it was concluded that J(gem) is −5.0 ± 1.0 Hz in methylene chloride. The absolute values for the coupling constants for 1 and 4 provide a measure of the inductive effect of the ring hetero group onJ.Values ofJ(gem) for 2 and 3 deviated from those predicted on the basis of the above inductive effect, suggesting lone pair contributions toJ(gem) ofc.+5.5 Hz per lone pair. With this estimate it was possible to predict accurately theJ(gem) values for 2‐t‐butyloxaziridine and 1‐t‐butyldiaziridine. The values ofJ(cis)andJ(trans)for 2 and 3 likewise suggested a contribution of −2.5 Hz toJ(cis)and −2.7 Hz toJ(trans)per lone pair. The present results suggest that the major factors causing positiveJ(gem) values in epoxides and aziridines are increasedscharacter to the CH bonds and lone pair effects, while the so‐called electronegativity effect actually operates in the opposite direction todecrease J(gem). Also, the unusually lowJ(vic) values of epoxides relative to cyclopropanes are now seen to be due more to negative lone pair contributions than to the el
ISSN:0030-4921
DOI:10.1002/mrc.1270130110
出版商:John Wiley&Sons Limited
年代:1980
数据来源: WILEY
|
10. |
15N NMR spectroscopy. 19—spectroscopic characterization of cyclodipeptides (2,5‐dioxopiperazines) |
|
Organic Magnetic Resonance,
Volume 13,
Issue 1,
1980,
Page 52-58
Hans R. Kricheldorf,
Preview
|
PDF (638KB)
|
|
摘要:
AbstractVarious cyclodipeptides containing glycine, alanine, leucine, valine, phenylalanine, phenylglycine and sarcosine units were synthesized by cyclization of dipeptide pentachlorophenyl esters. The13C and natural abundance15N NMR spectra of these heterocycles were measured in trifluoroacetic acid and compared with the spectra of the corresponding amino acids and polypeptides. The13C NMR carbonyl signals of all cyclodipeptides show a 1.5–4.0 ppm upfield shift relative to the corresponding polypeptides. The15N NMR signals show no such consistent relationship. The substituent effects and the neighbouring residue effects observed in the15N NMR spectra of the cyclodipeptides are different from those of polypeptides, while the one bond NH coupling constant ofcisandtransamide groups was almost identical. The nitrogen and the carbonyl signal of the Gly units in cyclo‐Gly‐Phe show an extraordinary downfield shift, reflecting the interaction of the phenyl group with the 2,5‐dioxopipera
ISSN:0030-4921
DOI:10.1002/mrc.1270130111
出版商:John Wiley&Sons Limited
年代:1980
数据来源: WILEY
|
|