Journal of the Chemical Society, Faraday Transactions, 1991
High-field Nuclear Magnetic Resonance and Molecular Investigations of Alditol Conformations in Aq... more High-field Nuclear Magnetic Resonance and Molecular Investigations of Alditol Conformations in Aqueous and Solvents ... Felix Franks" Pafra Ltd., Biopreservation Division, 150 Cambridge Science Park, Cambridge CB4 Josef Dadok, Sae Ying and Robert L. Kay Department of ...
3 J coupling constants for 2H exchanged pentitols in D2O, [2H5]pyridine and [2H6]acetone have bee... more 3 J coupling constants for 2H exchanged pentitols in D2O, [2H5]pyridine and [2H6]acetone have been determined at 25 °C after refinement by computer simulation of the fully resolved 1H n.m.r. spectra obtained at 620 MHz. There are significant differences between the coupling constants for aqueous and non-aqueous solvents but only minor differences between those for pyridine and acetone. A conformational analysis is proposed which is based on the observation that in solid crystals all the H—C—C—H dihedral angles are close to either 60°(gauche) or 180°(trans). From an application of the Karplus equation to the solution 3J values it appears unlikely that single unique conformations of the alditols exist in solution. Instead the results are interpreted in terms of different populations of rotamers that are rapidly equilibrating between dihedral angles of ±60 and 180°. Thermodynamic properties of the alditols in D2O are shown to be a reflection of the conformation of the specific pentitol in solution rather than that of the crystal structure.
We have investigated the ability of high‐resolution proton NMR spectroscopy to provide a biochemi... more We have investigated the ability of high‐resolution proton NMR spectroscopy to provide a biochemical constituent screening of human amniotic fluid (AF). Proton NMR spectra were obtained at 300 MHz on AF from patients undergoing amniocentesis in the mid‐trimester. Only AF from normal pregnancies (normal fetal karyotype, normal a‐fetoprotein levels, normal birth outcome) was used in this study. The AF supernatant was lyophilized and resuspended in deuterated water containing 0.1 mm phosphate buffer and 6.02 mm disodium maleate. Identification of low molecular weight compounds was confirmed by two‐dimensional NMR spectra (primarily correlated spectroscopy, or COSY) and standard addition techniques. A broad profile of compounds were ‘NMR visible’ in a single proton spectrum, including creatinine, glucose, organic acids (acetate, citrate, and lactate) and several amino acids (alanine, histidine, leucine, phenylalanine, tyrosine and valine). The proton spectrum was unaffected by prior freezing/thawing of AF samples. We were able to quantify compounds by comparison with an added concentration standard (maleate) at concentrations as low as 30 μm. Good agreement with literature values based on other analytical techniques was obtained.
Solid-state 2~AI and 29Si NMR spectroscopy with magic angle spinning (MAS) of samples was used to... more Solid-state 2~AI and 29Si NMR spectroscopy with magic angle spinning (MAS) of samples was used to study several 1.1 3 nm tobermorites, most of which were deliberately substituted with aluminium. 2~AI MASNMR clearly showed that aluminium is tetrahedrally co-ordinated in tobermorite structures. In addition two different aluminium environments resonating at -,~ 57 and 64 ppm from [AI(H20)6] 3+ were detected. 29Si MASNMR of pure, anomalous tobermorites showed resonances at -85.7 and -95.7 ppm from tetramethylsilane representing chain middle groups (Q2) and branching sites (Q3), respectively. Anomalous AIsubstituted tobermorites, on the other hand, showed two to four resonances representing different silicon environments. One AI-substituted tobermorite showed two resonances at -84.6 and -91.5ppm which were assigned to Qz (0AI) and Q3 (1 AI), respectively. In the above tobermorite aluminium appeared to have substituted into branching sites only. Two other AI-substituted tobermorites, howe...
Abstract The 29 Si MAS nmr spectra of highly dealuminated zeolites are shown to exhibit separate ... more Abstract The 29 Si MAS nmr spectra of highly dealuminated zeolites are shown to exhibit separate Si (OAl) resonances due to crystallographically inequivalent lattice sites. The chemical shift dispersion due to crystallographic inequivalence is of the same order of ...
... NORTHHOLLAND PUBLISHING COMPANY PROTON MAGNETIC RESONANCE STUDIES OF HUMAN ADULT HEMOGLOBIN I... more ... NORTHHOLLAND PUBLISHING COMPANY PROTON MAGNETIC RESONANCE STUDIES OF HUMAN ADULT HEMOGLOBIN IN ATERT Joseph J. BREEN, Dolores A. BERTOLI, Josef DADOK and Chien HO* Received 25 ... Columbus, Ohio, USA February 27 March 2, 1973. ...
Journal of the Chemical Society, Faraday Transactions, 1991
High-field Nuclear Magnetic Resonance and Molecular Investigations of Alditol Conformations in Aq... more High-field Nuclear Magnetic Resonance and Molecular Investigations of Alditol Conformations in Aqueous and Solvents ... Felix Franks" Pafra Ltd., Biopreservation Division, 150 Cambridge Science Park, Cambridge CB4 Josef Dadok, Sae Ying and Robert L. Kay Department of ...
3 J coupling constants for 2H exchanged pentitols in D2O, [2H5]pyridine and [2H6]acetone have bee... more 3 J coupling constants for 2H exchanged pentitols in D2O, [2H5]pyridine and [2H6]acetone have been determined at 25 °C after refinement by computer simulation of the fully resolved 1H n.m.r. spectra obtained at 620 MHz. There are significant differences between the coupling constants for aqueous and non-aqueous solvents but only minor differences between those for pyridine and acetone. A conformational analysis is proposed which is based on the observation that in solid crystals all the H—C—C—H dihedral angles are close to either 60°(gauche) or 180°(trans). From an application of the Karplus equation to the solution 3J values it appears unlikely that single unique conformations of the alditols exist in solution. Instead the results are interpreted in terms of different populations of rotamers that are rapidly equilibrating between dihedral angles of ±60 and 180°. Thermodynamic properties of the alditols in D2O are shown to be a reflection of the conformation of the specific pentitol in solution rather than that of the crystal structure.
We have investigated the ability of high‐resolution proton NMR spectroscopy to provide a biochemi... more We have investigated the ability of high‐resolution proton NMR spectroscopy to provide a biochemical constituent screening of human amniotic fluid (AF). Proton NMR spectra were obtained at 300 MHz on AF from patients undergoing amniocentesis in the mid‐trimester. Only AF from normal pregnancies (normal fetal karyotype, normal a‐fetoprotein levels, normal birth outcome) was used in this study. The AF supernatant was lyophilized and resuspended in deuterated water containing 0.1 mm phosphate buffer and 6.02 mm disodium maleate. Identification of low molecular weight compounds was confirmed by two‐dimensional NMR spectra (primarily correlated spectroscopy, or COSY) and standard addition techniques. A broad profile of compounds were ‘NMR visible’ in a single proton spectrum, including creatinine, glucose, organic acids (acetate, citrate, and lactate) and several amino acids (alanine, histidine, leucine, phenylalanine, tyrosine and valine). The proton spectrum was unaffected by prior freezing/thawing of AF samples. We were able to quantify compounds by comparison with an added concentration standard (maleate) at concentrations as low as 30 μm. Good agreement with literature values based on other analytical techniques was obtained.
Solid-state 2~AI and 29Si NMR spectroscopy with magic angle spinning (MAS) of samples was used to... more Solid-state 2~AI and 29Si NMR spectroscopy with magic angle spinning (MAS) of samples was used to study several 1.1 3 nm tobermorites, most of which were deliberately substituted with aluminium. 2~AI MASNMR clearly showed that aluminium is tetrahedrally co-ordinated in tobermorite structures. In addition two different aluminium environments resonating at -,~ 57 and 64 ppm from [AI(H20)6] 3+ were detected. 29Si MASNMR of pure, anomalous tobermorites showed resonances at -85.7 and -95.7 ppm from tetramethylsilane representing chain middle groups (Q2) and branching sites (Q3), respectively. Anomalous AIsubstituted tobermorites, on the other hand, showed two to four resonances representing different silicon environments. One AI-substituted tobermorite showed two resonances at -84.6 and -91.5ppm which were assigned to Qz (0AI) and Q3 (1 AI), respectively. In the above tobermorite aluminium appeared to have substituted into branching sites only. Two other AI-substituted tobermorites, howe...
Abstract The 29 Si MAS nmr spectra of highly dealuminated zeolites are shown to exhibit separate ... more Abstract The 29 Si MAS nmr spectra of highly dealuminated zeolites are shown to exhibit separate Si (OAl) resonances due to crystallographically inequivalent lattice sites. The chemical shift dispersion due to crystallographic inequivalence is of the same order of ...
... NORTHHOLLAND PUBLISHING COMPANY PROTON MAGNETIC RESONANCE STUDIES OF HUMAN ADULT HEMOGLOBIN I... more ... NORTHHOLLAND PUBLISHING COMPANY PROTON MAGNETIC RESONANCE STUDIES OF HUMAN ADULT HEMOGLOBIN IN ATERT Joseph J. BREEN, Dolores A. BERTOLI, Josef DADOK and Chien HO* Received 25 ... Columbus, Ohio, USA February 27 March 2, 1973. ...
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