Cysteine-sulphinic acid

The same group have used the enzyme combination employed in the aspartate deracemization cited above to deracemize 2-naphthylalanine, hut have made use of an interesting innovation introduced by Helaine et al to pull over the poised equilibrium of the transamination reaction. Cysteine sulphinic acid was used as the amino donor in the transamination. The oxoacid product spontaneously decomposes in to pyruvic acid and SO2 (Scheme 3). 

Universal thiol precursor (X—SH) of oxidation products Cysteine sulphinic acid (X—SCFH), Cysteic acid (X-SO-jH) Cystine (X-S-S-X) ... 

L-Aspartic Acid L-Cysteic Acid L-Cysteine Sulphinic Acid L-Glutamic Acid... 

Taurine - A glyclne-like, sulphur containing amino acid, taurine (12) is found in reasonably high concentrations throughout the mammalian central nervous system and in heart.In brain, taurine is formed as a result of the decarboxylation of cysteine sulphinic acid (15) to hypotau-rlne (8 ), which in turn is oxidized to form taurine.Like other transmitter candidates, taurine is accumulated and released by brain tissue and the accumulation can be inhibited by ouabain. Clinically, significant alterations in taurine levels may be associated with retinitis pigmentosa, epilepsy, mongolism, and possibly heart disease. 

It has been mentioned above that there are few naturally occurring sulphonic acids. One notable exception is taurine (6), which is formed biosynthetically in several steps. One of these steps involves the oxidation of either cysteine sulphinic acid or hypotaurine (both of which contain a sulphinic acid group) to sulphonic acids. This reaction is, of course,... 

Enzymatic decarboxylation169 of L-cysteic acid-35S (equation 86) by the tissues of chicken embryo has been investigated by Fromageot and coworkers170. Enzyme preparations from liver appeared to be the most active, and the authors determined [35S]taurine as well as unreacted 35S-cysteic acid, 35S-/Lsulphonylpyruvic acid and 35S-sulphate. The reaction is inhibited by L-cysteine sulphinic acid, by DL-a-methylcysteic acid, CH2ICOONa, NaCN and by hydroxylamine. The enzyme is activated by pyridoxal phosphate. 

The more complex sulphur requirements of the marine animals are met largely by cysteine, cystine, methionine, biotin, and thiamine (Young and Maw, 1958) (Fig. 4). Cysteine is a component of the tripeptide glutathione and a precursor of taurine. Methionine is as an essential amino acid involved in biosynthesis of proteins, creatine and adrenaline. Adenosylmethionine is considered to be the active part in transmethylation, e.g. of choline. Methionine is part of the pathways to homocysteine, cystathionine and methylthioadenosine (Young and Maw, 1958). Various organisms convert cysteine and/or cystine into mercapturic acids, cysteine sulphinic acid, and thiazolidine derivatives (Zobell, 1963). 

Wu J.-Y. (1982) Purification and characterization of cysteic/cysteine sulphinic acids decarboxylase and L-glutamate decarboxylase in bovine brain. Proc Natl Acad. Set. USA 79, 4270-4274. 

J.G. Jacobsen and L.H. Smith, Jr., Comparison of decarboxylation of cysteine sulphinic acid-l-C and cysteic acid-l-C by hximan, dog and rat liver and brain. 

Relatively few reports have been published subsequently on the use of these reagents. Hope and coworkers99 have used sodium in liquid ammonia to cleave the benzyl sulphonyl derivatives of cysteamine, L-cysteine and L-homocysteine to prepare the corresponding sulphinic acids, as in equation (42). 

The first reductive kinetic resolution of racemic sulphoxides was reported by Balenovic and Bregant. They found that L-cysteine reacted with racemic sulphoxides to produce a mixture of L-cystine, sulphide and non-reduced optically active starting sulphoxide (equation 147). Mikojajczyk and Para reported that the reaction of optically active phosphonothioic acid 268 with racemic sulphoxides used in a 1 2 ratio gave the non-reduced optically active sulphoxides, however, with a low optical purity (equation 148). It is interesting to note that a clear relationship was found between the chirality of the reducing P-thioacid 268 and the recovered sulphoxide. Partial asymmetric reduction of racemic sulphoxides also occurs when a complex of LiAlH with chiral alcohols , as well as a mixture of formamidine sulphinic acid with chiral amines, are used as chiral reducing systems. ... 

Cysteine Cys-disulphides mixed-disulphides Sulphenic acid, sulphinic acid, Sulphonic acid (via alkyl thioradicals)... 

Reactivity is not limited to direct addition to the phenoxyl ring structure, and reactions with thiols, amines and olefmic compounds have been reported. Both HOBr and HOCl can elicit oxidation of cysteine residues, where oxidation of the thiol moiety to a sulphinic acid is associated with activation of the latent form of matrix metalloproteinase-7 [111]. Higher doses of HOCl cause inactivation of the enzyme through site-specific modification of tryptophan and the adjacent glycine to yield an unknown product that lacks four mass units [112]. 

The only thiol oxidation reaction to oxy-derivatives of general biochemical significance is that of cysteine to alanine 3-sulphinic acid (cysteine sulphinic add) . This is thought to be the initial reaction in the... 

Cysteine-sulphinic add, by transamination, can yield j3-sulphinyl-pyruvic add which is decomposed into pyruvic acid and SO,— which... 

Hope, D.B., 1955, Pyridoxal phosphate as the coenzyme of the mammalian decarboxylase for L-cysteine sulphinic and L-cysteic acids, Biochem. J., 59 497-500. 

The principal component of the lachrymatory factor of the onion (Allium cepa) has been identified by flash vacuum pyrolysis (FVP)/microwave techniques as (Z)-propanethial 5-oxide, CH3CH2CH=S=0. It functions as a 1,3-dipole and as a dipolarophile, and it dimerizes in cold benzene to give principally trans-3,4-diethyl-1,2-dithietan 1,1-dioxide rather than 2,4-diethyl-1,3-dithietan 1,3-dioxide, as previously proposed. Formation of this sulphine from its cellular precursor, rran5-(+)-S-(prop-l-enyi)-L-cysteine sulphoxide, is suggested to involve the formation of a Schiff base and the elimination of ( )-prop-l-enesulphenic acid, which then rearranges to the sulphine (Scheme 2). 

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