Equilibrium thermodynamic studies for the formation of 1:1 complexes of CO and ethene with a rhodium(II) porphyrin metallo-radical

2001 ◽  
Vol 79 (5-6) ◽  
pp. 854-856 ◽  
Author(s):  
Leah Basickes ◽  
Andrew G Bunn ◽  
Bradford B Wayland
Keyword(s):  
Carbon Monoxide ◽  
Complex Formation ◽  
Equilibrium Thermodynamic ◽  
Nmr Studies ◽  
Thermodynamic Studies ◽  
H Nmr ◽  
Porphyrin Ligand ◽  
The One ◽  
Paramagnetic Shifts

Tetra(2,4,6 triisopropropyl phenyl)porphyrinatorhodium(II) ((TTiPP)RhII·1) is a persistent metal-centered radical with the odd electron in the rhodium(II) dz2 orbital. (TTiPP)RhII· forms 1:1 complexes with CO and CH2CH2 where the porphyrin ligand steric properties inhibit further reactions of the one-electron activated substrates. 1H NMR paramagnetic shifts at a series of temperatures are used in evaluating the thermodynamics for CO complex formation with 1 to form [(TTiPP)RhII(CO)]·2 (ΔH° = -5.5 ± 0.5 kcal mol-1; ΔS° = -9 ± 1 cal K-1 mol-1). Related 1H NMR studies show that the bonding of 1 with ethene is less favorable than CO.Key words: rhodium porphyrin, carbon monoxide, ethene, thermodynamics, complex formation, metal-centered radical.

Purification of a Specific Placental Plasminogen Activator Inhibitor by Monoclonal Antibody and Its Complex Formation with Plasminogen Activator

1985 ◽  
Vol 53 (01) ◽  
pp. 122-125 ◽  
Author(s):  
B Åstedt ◽  
Ingegerd Lecander ◽  
T Brodin ◽  
A Lundblad ◽  
Karin Löw
Keyword(s):  
Monoclonal Antibody ◽  
Complex Formation ◽  
Plasminogen Activator ◽  
Plasminogen Activator Inhibitor ◽  
Tissue Type ◽  
System A ◽  
The One ◽  
Fast Acting ◽  
Chain Form ◽  
Activator Inhibitor

SummaryA monoclonal antibody of IgG2a-type was obtained against a specific fast acting plasminogen activator inhibitor found in placenta. The placental inhibitor was purified by affinity chromatography using the monoclonal antibody and additionally in a FPLC-system. A strong complex formation was found between the inhibitor and urokinase and also with the two-chain form of plasminogen activator of the tissue-type. A weaker complex was found between the placental inhibitor and the one- chain form of the tissue-type activator.

1H NMR Conformational Studies in Water of Angiotensin II Analogues Modified at the N- and C-Termini: Interactions of the Aromatic Side Chains and Folding of the N-Terminal Domain

1994 ◽  
Vol 59 (11) ◽  
pp. 2523-2532 ◽  
Author(s):  
John Hondrelis ◽  
John Matsoukas ◽  
George Agelis ◽  
Paul Cordopatis ◽  
Ning Zhou ◽  
...  
Keyword(s):  
Shielding Effect ◽  
Resonance Spectroscopy ◽  
Nmr Studies ◽  
Previous Suggestion ◽  
Aminoisobutyric Acid ◽  
H Nmr ◽  
Neutral Ph ◽  
Angiotensin Ii Analogues ◽  
Proton Resonances ◽  
Cosy Nmr

The conformation of [Sar1]angiotensin II in water at neutral pH has been examined by proton magnetic resonance spectroscopy at 400 MHz and in particular by comparing its 1H NMR spectral data with those of analogues modified at positions 1,4 and 6, namely [Sar1,Cha8]ANGII, [Des Asp1,Cha8]ANGII, [Aib1,Tyr(Me)4]ANGII, [Aib1,Tyr(Me)4,Ile8]ANGII, [N-MeAib1,Tyr(Me)4]ANGII, [N-MeAib1,Tyr(Me)4,Ile8]ANGII, ANGIII and [Sar1,Ile8]ANGII. Assignment of all proton resonances in these analogues was made possible by 2D COSY NMR experiments. The H-2 and H-4 protons for the histidine ring in [Sar1]ANGII, ANGII and ANGIII were shielded compared with the same protons in [Sar1,Ile8]ANGII, [Sar1,Cha8]ANGII and [Des Asp1,Cha8]ANGII; this shielding effect was not disturbed upon methylation of the tyrosine hydroxyl and/or replacement of residue 1 (sarcosine or aspartic acid) with aminoisobutyric acid (Aib) or N-methyl aminoisobutyric acid (N-MeAib). These data are consistent with our previous suggestion based on NMR studies in neutral DMSO that a characteristic folded conformation for ANGII previously observed in non-polar solvents can also be detected in water at neutral pH, but to a lesser degree.

High field 1H NMR Studies of Sol-Gel Kinetics

1986 ◽  
Vol 73 ◽  
Author(s):  
Bruce D. Kay ◽  
Roger A. Assink
Keyword(s):  
Equilibrium Distribution ◽  
Sol Gel ◽  
Nmr Studies ◽  
H Nmr ◽  
Rate Limiting Step ◽  
Rate Of Hydrolysis ◽  
Acid Catalyzed ◽  
Product Species ◽  
Rate Limiting ◽  
Kinetics Of

ABSTRACTHigh resolution 1H NMR spectroscopy at high magnetic fields is employed to study the reaction kinetics of the Si(OCH3)4:CH3OH:H2O sol-gel system. Both the overall extent of reaction as a function of time and the equilibrium distribution of species are measured. In acid catalyzed solution, condensation is the rate limiting step while in base catalyzed solution, hydrolysis becomes rate limiting. A kinetic model in which the rate of hydrolysis is assumed to be independent of the adjacent functional groups is presented. This model correctly predicts the distribution of product species during the initial stages of the sol-gel reaction.

The synthesis of 11R- and 11S-HETE and of 11-R,S-HPETE methyl esters

1983 ◽  
Vol 61 (4) ◽  
pp. 712-717 ◽  
Author(s):  
George Just ◽  
Corinne Luthe ◽  
Minh Tan Phan Viet
Keyword(s):  
Methyl Esters ◽  
Nmr Studies ◽  
H Nmr ◽  
Conformational Properties

Methyl 11R- and 11S-hydroxyeicosa-5Z,8Z,12E,14Z-tetraenoate (17R, 17S) (11-HETE) and the corresponding 11-hydroperoxide 19 (11-HPETE) have been prepared from readily available starting materials. The yields were approximately 25% for 11R,S-HETE, and 5% each for 11R- and 11S-HETE.Extensive 400 MHz 1H nmr studies of 17 (nOe difference, 2D J-resolved) were undertaken to confirm the structure. Some conformational properties are discussed.

scholarly journals Energy Conservation Model Based on Genomic and Experimental Analyses of a Carbon Monoxide-Utilizing, Butyrate-Forming Acetogen, Eubacterium limosum KIST612

2015 ◽  
Vol 81 (14) ◽  
pp. 4782-4790 ◽  
Author(s):  
Jiyeong Jeong ◽  
Johannes Bertsch ◽  
Verena Hess ◽  
Sunju Choi ◽  
In-Geol Choi ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Atp Synthesis ◽  
Binding Motif ◽  
Oxidation Of Co ◽  
Co Dehydrogenase ◽  
Content Type ◽  
A Genome ◽  
Eubacterium Limosum ◽  
The One ◽  
Conservation Model

ABSTRACTEubacterium limosumKIST612 is one of the few acetogens that can produce butyrate from carbon monoxide. We have used a genome-guided analysis to delineate the path of butyrate formation, the enzymes involved, and the potential coupling to ATP synthesis. Oxidation of CO is catalyzed by the acetyl-coenzyme A (CoA) synthase/CO dehydrogenase and coupled to the reduction of ferredoxin. Oxidation of reduced ferredoxin is catalyzed by the Rnf complex and Na+dependent. Consistent with the finding of a Na+-dependent Rnf complex is the presence of a conserved Na+-binding motif in thecsubunit of the ATP synthase. Butyrate formation is from acetyl-CoA via acetoacetyl-CoA, hydroxybutyryl-CoA, crotonyl-CoA, and butyryl-CoA and is consistent with the finding of a gene cluster that encodes the enzymes for this pathway. The activity of the butyryl-CoA dehydrogenase was demonstrated. Reduction of crotonyl-CoA to butyryl-CoA with NADH as the reductant was coupled to reduction of ferredoxin. We postulate that the butyryl-CoA dehydrogenase uses flavin-based electron bifurcation to reduce ferredoxin, which is consistent with the finding ofetfAandetfBgenes next to it. The overall ATP yield was calculated and is significantly higher than the one obtained with H2+ CO2. The energetic benefit may be one reason that butyrate is formed only from CO but not from H2+ CO2.

scholarly journals 1H NMR Studies of Surfactants in Aqueous Solutions

2003 ◽  
Vol 19 (07) ◽  
pp. 675-680 ◽  
Author(s):  
Mao Shi-Zhen ◽  
◽  
Du You-Ru
Keyword(s):  
Aqueous Solutions ◽  
Nmr Studies ◽  
H Nmr

ChemInform Abstract: (19)F- AND (1)H-NMR STUDIES OF RING-FLUORINATED IMIDAZOLES AND HISTIDINES

1975 ◽  
Vol 6 (42) ◽  
pp. no-no
Author(s):  
HERMAN J. C. YEH ◽  
KENNETH L. KIRK ◽  
LOUIS A. COHEN ◽  
JACK S. COHEN
Keyword(s):  
Nmr Studies ◽  
H Nmr
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