The Kinetics and Mechanism of Reduction of Electron Transfer Proteins and Other Compounds of Biological Interest by Dithionite

Lambeth, David O.; Palmer, Graham

doi:10.1016/s0021-9258(19)43514-x

Cited by 320 publications

(92 citation statements)

References 20 publications

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“…There is only limited information on the thermodynamic strength of the interannular bond in thiatriazine dimers. The dissocation constant of (Ph2CZNIS)2 is consider9bly greater (3 x 10 ' M in CH,Cl,) (262) than that of dithionite (10 -"A4 in H'O) (321), in accord with the observed trend in S---S distances. but may well be dependent on the nature of the 3,s substituents and solvation effects.…”

Section: Radical Associations and Rearrangementssupporting

confidence: 75%

Cyclic and Heterocyclic Thiazenes

Oakley

1988

Progress in Inorganic Chemistry

127

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Scheme I1A second binary compound, tetrasulfur dinitride (S4N2, 4), was also isolated before the end of the last century (32). Its correct elemental composition, however, was not established until 1925 (33), and its molecular formula not confirmed until 1951 (34). Early estimates suggested the formula N2Sj (32), an observation that attests to the tendency of the molecule to disproportionate above its melting point of 22.5"C (hence, the high sulfur content). The six-membered ring structure with a half-chair conformation was finally confirmed in 1981 (35,36). Most early preparative methods involved a thermal decomposition, for example, of S4N, in the presence of sulfur and/or carbon disulfide (37,38). More recently the use of simple metathetical reactions, for example, between Ni(S2N2H)? and S2CI2 has been explored (39). A simple procedure involving the reaction of aqueous ammonia with sulfur monochloride has also been developed (40); although the yield is low (<2%), the method provides a convenient preparation of small quantities (<0.5 g) starting from commercially available materials (3%). The solid state polymerization of S4N2 to (SN), ( 5 ) has recently been reported (36); this process is presumably initiated by trace amounts of (radical) impurities since, when recrystallized from diethyl ether, solid S,N, is indefinitely stable below its melting point (3%).Disulfur dinitride (6) (Scheme 11) was first generated (inadvertently) by Burt in 1910 (41) during an attempt to remove sulfur impurities from SJNJ by passing a vaporous mixture of the two over finely divided silver. At the time he noted the formation of a blue film [later characterized as (SN), polymer]. This reaction has been studied extensively since then, and now 304 RICHARD T. OAKLEY

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Section: Radical Associations and Rearrangementssupporting

confidence: 75%

Cyclic and Heterocyclic Thiazenes

Oakley

1988

Progress in Inorganic Chemistry

127

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“…Publications studying deoxygenated Hb reacting with oxygen and several biomolecules including spinach ferredoxin, horse metmyoglobin, horse heart ferricytochrome with dithionite report reactions occurring on the order of milliseconds [49]. While using a basic spectrophotometer rather than a robust, airtight stopped-flow spectrophotometer, we qualitatively observed a very rapid deoxygenation of Hb, confirming literature observations.…”

Section: Reactions With Free Hemoglobin From Healthy Donorssupporting

confidence: 87%

Magnetophoretic and spectral characterization of oxyhemoglobin and deoxyhemoglobin: Chemical versus enzymatic processes

et al. 2021

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A new method for hemoglobin (Hb) deoxygenation, in suspension or within red blood cells (RBCs) is described using the commercial enzyme product, EC-Oxyrase®. The enzymatic deoxygenation method has several advantages over established deoxygenation methodologies, such as avoiding side reactions that produce methemoglobin (metHb), thus eliminating the need for an inert deoxygenation gas and airtight vessel, and facilitates easy re-oxygenation of Hb/RBCs by washing with a buffer that contains dissolved oxygen (DO). The UV-visible spectra of deoxyHb and metHb purified from human RBCs using three different preparation methods (sodium dithionite [to produce deoxyHb], sodium nitrite [to produce metHb], and EC-Oxyrase® [to produce deoxyHb]) show the high purity of deoxyHb prepared using EC-Oxyrase® (with little to no metHb or hemichrome production from side reactions). The oxyHb deoxygenation time course of EC-Oxyrase® follows first order reaction kinetics. The paramagnetic characteristics of intracellular Hb in RBCs were compared using Cell Tracking Velocimetry (CTV) for healthy and sickle cell disease (SCD) donors and oxygen equilibrium curves show that the function of healthy RBCs is unchanged after EC-Oxyrase® treatment. The results confirm that this enzymatic approach to deoxygenation produces pure deoxyHb, can be re-oxygenated easily, prepared aerobically and has similar paramagnetic mobility to existing methods of producing deoxyHb and metHb.

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“…2À and the dissociation of the S 2 O 4 2À will form two molecules of the SO 2 À c radical anion (Scheme 2). 45 A higher fraction of water in the system promotes the efficient dissolution of the dithionite salt and consequently its dissociation into SO 2 À c. 20,28 It is important to note that the dissociation constant of S 2 O 4 2À in water is very small, K d $ 10 À6 mM 45,46 but it increases with the decrease of the polarity of the solvent. 47 Nevertheless, the data in Fig.…”

Section: Feeding Of Na 2 S 2 Omentioning

confidence: 99%