The reaction of S-nitrosothiols with thiols at high thiol concentration

1998 ◽  
Vol 76 (6) ◽  
pp. 789-794 ◽  
Author(s):  
Andrew P Dicks ◽  
E Li ◽  
Andrew P Munro ◽  
Helen R Swift ◽  
D Lyn H. Williams
Keyword(s):  
Nitric Oxide ◽  
Metal Ion ◽  
Large Range ◽  
Ph Dependence ◽  
Large Excess ◽  
Marked Contrast ◽  
First Order ◽  
Thiolate Anion ◽  
Rapid Equilibrium

Reactions of S-nitrosothiols (RSNO) with their corresponding thiols (RSH) present in a large excess (>20-fold) proceed readily to give the disulfide. Ammonia is formed together with some nitrite anion, and these constitute >90% of the "nitrogen" products. This is in marked contrast with the reaction at low thiol concentration, where nitric oxide is the major initial "nitrogen" product, which is rapidly converted in the presence of oxygen in water to nitrite anion. Also in marked contrast to the "low thiol concentration" reaction, the reaction at high thiol concentration is not affected by added Cu2+, nor by the metal-ion scavenger EDTA. Kinetically all reactions were excellent first-order processes, and the reactions were also strictly first order in thiol concentration. A large range of nitrosothiols were studied and the generality of the reaction established. Some reactions of RSNO with other thiols (R'SH) were examined and the results readily interpreted in terms of a prior rapid equilibrium transnitrosation. The pH dependence for the reaction of S-nitrosocysteine with cysteine clearly showed that the reactive species is the cysteine thiolate anion. The results are discussed along with those of two other recent reports of these reactions, in terms of thiolate attack initially at the nitroso nitrogen atom, and subsequently at sulfur atoms, eliminating RSSR and yielding hydroxylamine, which is rapidly reduced by thiolate ion to ammonia. The results are also discussed in connection with the release of NO from nitrosothiols and with the important biological consequences, both for the in vivo reactions of NO and for the potential of nitrosothiols as NO-releasing drugs for medical use.Key words: S-nitrosothiols, thiols, nitric oxide, ammonia, nitrous oxide.

scholarly journals Kinetics and mechanism of sol-gel transformation between some trivalent- and tetravalent-metal ions and Sodium alginate Anionic polyelectrolyte with formation of coordination Biopolymeric structure polymembranes Hydrogels of Capillary Structures Ex

2007 ◽  
Vol 3 (1) ◽  
pp. 133-142 ◽  
Author(s):  
Ishaq Abdullah Zaafarany
Keyword(s):  
Sodium Alginate ◽  
Metal Ion ◽  
Sol Gel ◽  
Coordination Geometry ◽  
Large Excess ◽  
First Order ◽  
Pseudo First Order ◽  
The Stability ◽  
Kinetics Of ◽  
Overall Kinetics

Abstract          The kinetics of sol-gel transformation between A13+, La 3+ and Th4+ metal ion electrolytes and sodium alginate sol have been studied complexometrically at various  temperatures. In the presence of a large excess of sodium alginate sol concentration over that of metal ion electrolyte, the pseudo first–order plots of exchange showed sigmoidal curves with two distinct stages. The initial part was relatively fast and curved significantly at early times, followed by a slow decrease in the rates of exchange over longer time periods. The rate constants of gelation showed second-order overall kinetics which was first order in the concentration of both reactants. The thermodynamic parameters have been evaluated and tentative gelation mechanisms consistent with the kinetic results of gelation are suggested. The stability of these ionotropic metal-alginate complexes has been discussed in terms of the coordination geometry and strength of chelated bonds.

Urinary prostaglandin F2α excretion is not pH-dependent in the conscious rat: implications for the urinary prostaglandin E2/prostaglandin F2α ratio

1990 ◽  
Vol 78 (2) ◽  
pp. 181-184 ◽  
Author(s):  
J. Haylor ◽  
C. J. Lote
Keyword(s):  
Excretion Rate ◽  
Ph Dependence ◽  
Prostaglandin F2α ◽  
Urine Ph ◽  
Marked Contrast ◽  
Conscious Rat ◽  
Alkaline Urine ◽  
Site Of Action ◽  
Accurate Reflection

1. The influence of urine pH on the urinary excretion of prostaglandin (PG) F2α and the PGE2/PGF2α ratio has been examined in the conscious rat. 2. The basal urinary PGF2α excretion rate of 3.9 pmol/h (n = 23) did not vary with urine pH. In marked contrast, PGE2 excretion increased as the urine became more alkaline. The PGE2/PGF2α ratio therefore progressively increased from 1.5 to 22 as the pH of the urine changed from pH 5.8 to pH 7.8. 3. The independence of PGF2α excretion from urine pH: (a) excludes cyclo-oxygenase as a potential site of action for the pH-dependence of urinary PGE2 excretion; (b) suggests that the urinary PGE2/PGF2α ratio measured in alkaline urine may be a more accurate reflection of the kidneys, ability to synthesize these two prostaglandins in vivo; (c) suggests that control of urine pH is required before the urinary PGE2/PGF2α ratio can be employed as an index of PGE2 9-ketoreductase (EC 1.1.1.189) activity in vivo.

Kinetik der Reaktion von 2.4-Dinitrofluorbenzol mit Imidazol-, SH- und Imidazol-SH-Verbindungen / Kinetics of the Reaction of 2,4-dinitro-1-fluorobenzene with Imidazole-, SH- and Imidazole-SH-compounds

1971 ◽  
Vol 26 (10) ◽  
pp. 1010-1016 ◽  
Author(s):  
Renate Voigt ◽  
Helmut Wenck ◽  
Friedhelm Schneider
Keyword(s):  
Temperature Dependence ◽  
Rate Constants ◽  
Reaction Rate ◽  
Ph Dependence ◽  
First Order ◽  
Molecular Transfer ◽  
Thiolate Anion ◽  
Nucleophilic Reactivity ◽  
Kinetics Of ◽  
Lindley Equation

First order rate constants of the reaction of a series of SH-, imidazole- and imidazole/SH-compounds with FDNB as well as their pH- and temperature dependence were determined. Some of the tested imidazole/SH-compounds exhibit a higher nucleophilic reactivity as is expected on the basis of their pKSH-values. This enhanced reactivity is caused by an activation of the SH-groups by a neighbouring imidazole residue. The pH-independent rate constants were calculated using the Lindley equation.The kinetics of DNP-transfer from DNP-imidazole to SH-compounds were investigated. The pH-dependence of the reaction displays a maximum curve. Donor in this reaction is the DNP-imidazolecation and acceptor the thiolate anion.The reaction rate of FDNB with imidazole derivatives is two to three orders of magnitude slower than with SH-compounds.No inter- or intra-molecular transfer of the DNP-residue from sulfure to imidazole takes place.

scholarly journals Synthesis of N-Pyridin-2-ylmethyl and N-Quinolin-2-ylmethyl ­Substituted Ethane-1,2-diamines

SynOpen ◽  
2017 ◽  
Vol 01 (01) ◽  
pp. 0147-0155 ◽  
Author(s):  
Yi-Qiu Yang ◽  
Long-Zhi Ke ◽  
Gui-Fei Wang ◽  
Shu-Yong Song ◽  
Ming-Ning Qiu ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Metal Ions ◽  
Targeted Delivery ◽  
Metal Ion ◽  
Synthesis And Characterization ◽  
Long Wavelength ◽  
Initial Work ◽  
Wavelength Light

Two N-(2-(bis(pyridin-2-ylmethyl)amino)ethyl)quinoline-2-carboxamides and two N-(2-(bis(quinolin-2-ylmethyl)amino)ethyl)quinoline-2-carboxamides have been synthesized. These structures contain five nitrogen atoms that can form coordinate bonds with metal ions such as Mn(II) and Fe(II). An additional coordinating bond can be formed between the metal ion and a neutral molecule of nitric oxide (NO). The resultant complexes are potentially useful agents for targeted delivery of NO to in vivo biological sites such as tumors, where the NO is released upon irradiation with long-wavelength light. Initial work involving the synthesis and characterization of these analogues is reported here.

Kinetics and mechanisms of the thermal decomposition of propane II. The reaction inhibited by nitric oxide

1962 ◽  
Vol 270 (1341) ◽  
pp. 254-266 ◽  
Keyword(s):  
Nitric Oxide ◽  
Volume Ratio ◽  
Inflexion Point ◽  
Kcal Mole ◽  
Large Excess ◽  
First Order ◽  
Partial Pressures ◽  
Pressure Time ◽  
Initiation Reaction ◽  
Kinetics Of

The kinetics of the pyrolysis of propane inhibited by nitric oxide were investigated from 640 to 560 °C and at partial pressures of propane from 25 to 550 mm Hg. The pressure-time curves were found to be S-shaped, and the induction period was lengthened considerably as the propane pressure was lowered. Complete inhibition by nitric oxide was obtained with 10 to 12% nitric oxide. The initial rates were found to be proportional to the 3/2 power of the pressure over most of the temperature range, and to a slightly lower power at the highest temperatures. The orders of reaction corresponding to the inflexion point are close to unity at the highest temperatures, and increase steadily as the temperature is lowered. The activation energy calculated from the inflexion rates in the first-order region was 69.4 kcal/ mole. The rates decreased with an increase in the surface to volume ratio. The addition of a large excess of carbon dioxide had no effect on the fully inhibited rates. The results are shown to be consistent with a mechanism in which the initiation reaction involves the abstraction of a hydrogen atom from propane by nitric oxide, and in which the termination reaction is between HNO and a propyl radical.

Nitric Oxide Is Responsible for Flow-Dependent Dilatation of Human Peripheral Conduit Arteries In Vivo

Circulation ◽  
1995 ◽  
Vol 91 (5) ◽  
pp. 1314-1319 ◽  
Author(s):  
Robinson Joannides ◽  
Walter E. Haefeli ◽  
Lilly Linder ◽  
Vincent Richard ◽  
El Hassan Bakkali ◽  
...  
Keyword(s):  
Nitric Oxide

In Vivo Spin Trapping of Glyceryl Trinitrate–Derived Nitric Oxide in Rabbit Blood Vessels and Organs

Circulation ◽  
1995 ◽  
Vol 92 (7) ◽  
pp. 1876-1882 ◽  
Author(s):  
Alexander Mülsch ◽  
Peter Mordvintcev ◽  
Eberhard Bassenge ◽  
Frank Jung ◽  
Bernd Clement ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Glyceryl Trinitrate ◽  
Blood Vessels ◽  
Spin Trapping ◽  
Rabbit Blood
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