Thioglycolic acid reduction with

Formazans and their metal complexes are used as textile dyes by direct application. The in situ reduction of tetrazolium salts has not been used to introduce the dyes to their substrates. Treatment with triaryl mono and bis tetrazolium salts followed by a reducing agent such as ascorbic acid or thioglycolic acid has been claimed as a method of introducing formazans as permanent hair dyes.641 There are some references to their use as therapeutic agents.642 544... 

A development reported recently [519] involves reduction of the cystine disulphide bonds in wool with either thioglycolic acid or tetrakis(hydroxymethyl)phosphonium chloride to form thiol groups, followed by crosslinking with bifunctional reactive dyes. This gave improved insect resistance but had adverse effects on physical properties such as strength, shrinkage and stiffness, thus limiting the potential of the process for commercial use. 

Many extracellular proteins like immunoglobulins, protein hormones, serum albumin, pepsin, trypsin, ribonuclease, and others contain one or more indigenous disulfide bonds. For functional and structural studies of proteins, it is often necessary to cleave these disulfide bridges. Disulfide bonds in proteins are commonly reduced with small, soluble mercaptans, such as DTT, TCEP, 2-mercaptoethanol, thioglycolic acid, cysteine, etc. High concentrations of mercaptans (molar excess of 20- to 1,000-fold) are usually required to drive the reduction to completion. 

NH2OH HC1, NH3, NOt, 1,10-phenanthroline, S2-, SCN- + SO -, S20(-, sulfosalicylate, tartrate, thioglycolic acid, thiosemicarbazide, thiocarbohydrazide, thiourea Fe Acetylacetone, (reduction with) ascorbic acid, C2OJ-, citrate, CN-, 2,3-dimercaptopropanol,... 

Acetate, (C6H5)4AsC1, citrate, 2,3-dimercaptopropanol, EDTA, I-, Na5P3O10, SO)-, S20)-, tartrate, tiron, tetraphenylarsonium chloride, triethanolamine, thioglycolic acid Acetylacetone, citrate, CN-, EDTA, I-, NH3, N02, SCN-, S20)-, tartrate, triethanol amine Citrate, CN-, EDTA, I-, NH3, N02, SCN-, S20 -, tartrate, urea Reduction to Pu(IV) with sulfamic acid C20)-, citrate, EDTA, F-, tartrate Oxidation to perrhenate Citrate, tartrate, thiourea CN-, thiourea... 

In view of its importance, reductive dissolution of Fe oxides has been widely studied. Reductants investigated include dithionite, thioglycolic acid, thiocyanate, hydrazine, ascorbic acid, hydroquinone, H2S, H2, Fe ", tris (picolinato) V", fulvic acid, fructose, sucrose and biomass/bacteria (Tab. 12.3). Under the appropriate conditions, reductive dissolution may also be effected photochemically. As with protonation, the extent of reduction may be strongly influenced by ligand and proton adsorption on the oxide surface. 

Ferric ions and complexes in aqueous media react readily with cysteine (13, 21) or thioglycollic acid (14, 22) to form purple complexes which rapidly change to the ferrous form with accompanying formation of disulfides. It was not unreasonable, therefore, to assume that such a reaction provided rapid production of RS radicals in the initial stages of co-oxidation and that this rate should decrease as reduction to ferrous occurred. Eventually reoxidation of ferrous to ferric by peroxide would assert itself, and the rate could rise again. 

Successive reduction of l,3-dimethyl-4,5,6,7-tetrahydrobenzo[c]-thiophen-4-one (Section III,C) with sodium borohydride and dehydration of the resulting alcohol with polyphosphoric acid gives the unstable 1,3-dimethyl derivative [(18) R = H] in excellent yield,35 and successive treatment of the same ketone with methylmagnesium iodide and acid gives the 1,3,7-trimethyl derivative [(18) R=Me] (Table IV) and a second compound which is reported to be a dimer. 36 When l,3-dimethyl-4,5,6,7-tetrahydrobenzo[c]thiophen-4-one is treated with a mixture of phosphorus oxychloride and dimethyl-formamide (Vilsmeier-Haack formylation), it gives compound 19, which yields 20 on being treated successively with thioglycolic acid... 

Ferritin induced nanoparticle synthesis was adapted from a number of different synthetic strategies reliant upon the physical nature of ferritin. For instance, ferritin can readily exist in two stable forms (native ferritin with an intact iron oxide core or apo-ferritin lacking a mineral core) owing to the enhanced structural integrity of the protein shell. As a result, two general reaction schemes were adopted. The first route utilized the iron oxide core of native or reconstituted ferritin as a precursor to different mineral phases and types of iron nanoparticles, while the second invokes mineralization within the empty cavity of apo-ferritin. In the latter approach, the native protein must be demetallated by reductive dissolution with thioglycolic acid to yield apo-ferritin. Ultimately, apo-ferritin provides a widely applicable means to the synthesis of various nanoparticle compositions under many conditions. 

The pentadecapeptide Met-f -sulfoxide (20 mg, 0.01 mmol) was incubated in 1% aq thioglycolic acid (25 mL) at 45 °C for 24 h, the thioglycolic acid was then exchanged for acetate on an IRA-400 column by eluting with H2O. Freshly distilled thioglycolic acid was added to make a 1% soln. The incubation and ion exchange steps were carried out three times and the final aq soln was lyophilized yield 20 mg (92 %) amino acid analysis of the aminopeptidase M digest confirmed quantitative reduction of the Met(O) residue. 

Microemulsions have also been investigated for the use in chemical hair treatment [14]. Permanent wave products are based on the reduction of hair keratine cystine, which weakens the protein structure and allows a manipulation of the hair shape. Savelli et al. compared the cystine reduction obtained by thioglycolic acid in water with that obtained by a microemulsion. The microemulsion is based on the anionic surfactant sodium dode-cylsulphate, the co-surfactant pentanol and dodecane as the unpolar oil component. The cysteine formation is evaluated over a time period of 5 min. The experimental data are... 

Actual compound formation also occurs between the dehydroascorhic acid and GSH reactants, though little attention has been paid to this condensation. Complexes of dehydroascorhic acid with one molecule of either GSH or thioglycolic acid were formed by Drake et al. (D19) in acetic acid solutions. Disappearance of iodine-titrable -SH groups and appearance of a new levorotatory material indicated the complex formation. This continued until an equilibrium was reached in about one hour at 0°C. At equilibrium more than half the dehydroascorhic acid was complexed. Remarkably little reduction of dehydroascorhic by the sulfhydryl compound occurred, since this reaction becomes significant only at neutral pH s. The complex is probably a thiosemiacetal, similar to... 

Leach and O Donnell [15] have shown that the complete reduction of wool fiber with thioglycolic acid can be approached at pH 6.9 by employing extremely large concentrations of mercaptan (II) relative to keratin cystine (I). Similar results have been reported for the reduction of wool fiber with mercaptoethanol [16]. 

The reduction of cystine to give cysteine can be performed for example with tin in hydrochloric acid, with sodium in liquid ammonia, or catalytically with hydrogen and palladium black. Reduction can also be performed by use of an excess of a thiol, for example thioglycolic acid or dithiothreitol (the thieo-isomer of l,4-dimercaptobutan-2,3-diol) (XXXIV) (Cleland, 1964) ... 

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