Acids cysteic

Eeather meal, first hydroly2ed and then oxidi2ed, produces cysteic acid [13100-82-8] an excellent precursor for taurine in cats (20). Hydroly2ed feather meal may supplement the taurine provided by other dietary animal proteins and help replace part or all of the synthetic taurine in cat food formulations with considerable cost savings. 

Na/NH3, -30°, 3 min, 1(X)% yield. This protective group is stable to acidic hydrolysis (4.5 N HBr/HOAc 1 N HCV, CF3CO2H, reflux). There is no evidence of S N acyl migration in 5-(A-ethylcarbamates) (RS = cysteinyl). Oxidation of 5-(A-ethylcarbamoyl)cysteine with performic acid yields cysteic acid. ... 

Cystamine dihydrochloride, S,5-(L,L)-Cystathionine, Cysteamine, Cysteamine hydrochloride, ( )-Cysteic acid, S-Cysteic acid (H2O), L-Cysteine hydrochloride (H2O), ( )-Cysteine hydrochloride and L-Cystine, Cytidine, see entries in Chapter 6. 

Cysteic acid (3-sulfoalanine, l-amino-3-sulfopropionic acid) [13100-82-8, 3024-83-7] M 169.2, m 260"(dec). Likely impurities are cystine and oxides of cysteine. Crystd from water by adding 2 volumes of EtOH. When recrystd from aqueous MeOH it has m 264-266°, and the anhydrous acid has m 260°(dec). [Chapeville and Formageot Biochim Biophys Acta 26 538 1957 J Biol Chem 72 435 1927.]... 

The advantages of this method are a short reaction time and the nonfluorescence of the OPA reagent. Therefore, excess reagent must not be removed before the chromatography stage. Using this method, it is possible to measure tryptophan, but not secondary amino acids such as proline or hydroxyproline. Cysteine and cystine can be measured, but because of the low fluorescence of their derivatives, they must be detected using an UV system, or alternatively oxidized to cysteic acid before reaction. 

The opening of N-unsubstituted aziridine-2-carboxlic esters with sodium bisulfite was recently described by Xu [113]. Thus, treatment of (S)-151 (Scheme 3.54) with NaHS03 followed by NaOH afforded (J )-cysteic acid 152 in 74% yield. (S)-Cysteic acid was prepared similarly in 72 % yield. 

To the methods reviewed in an earlier volume 1 may be added the preparation by the oxidation of cystamine 2 and by the decarboxylation of cysteic acid.3 The method given in the procedure has appeared recently in the literature.4... 

Nishimura and coworkers57-59 studied the y-radiolysis of aqueous solutions of sulfoxide amino acids. Sulfoxide amino acids are the precursors of the flavors of onions (S-propyl-L-cysteine sulfoxide, S-methyl-L-cysteine sulfoxide and S-(l-propenyl)-L-cysteine sulfoxide) and garlic (S-allyl-L-cysteine sulfoxide). In studies on sprout inhibition of onion by /-irradiation it was found that the characteristic flavor of onions became milder. In the y-radiolysis of an aqueous solution of S-propyl-L-cysteine sulfoxide (PCSO)57,58 they identified as the main products alanine, cysteic acid, dipropyl disulfide and dipropyl sulfide. In the radiolysis of S-allyl-L-cysteine sulfoxide (ACSO) they found that the main products are S-allyl-L-cysteine, cysteic acid, cystine, allyl alcohol, propyl allyl sulfide and diallyl sulfide. The mechanisms of formation of the products were partly elucidated by the study of the radiolysis in the presence of N20 and Br- as eaq - and OH radicals scavengers, respectively. 

In the case of PCSO the addition of N20 leads to increased formation of cysteic acid, alanine and dipropyl sulfide and to a decrease in the yield of dipropyl disulfide. The addition of KBr decreases the yield of all the four products. These findings indicate that cysteic acid and alanine are formed by the reaction of OH radicals in parallel reactions as given in Figure 7. 

Figure 4-3. Oxidative cleavage of adjacent polypeptide chains linked by disulfide bonds (shaded) by per-formic acid (left) or reductive cleavage by 3-mercap-toethanol (right) forms two peptides that contain cysteic acid residues or cysteinyl residues, respectively.

Warenycia MW, Steele JA, Karpinski E, et al. 1989d. Hydrogen sulfide in combination with taurine or cysteic acid reversibly abolishes sodium currents in neuroblastoma cells. Neurotoxicology 10 191-199. 

Oxidative bleaching of wool is invariably carried out with hydrogen peroxide. The active species involved is likely to be the same as on cellulosic substrates but specific reactions with wool amino acid residues must be considered. The primary reaction is oxidation of cystine disulphide bonds leading to the formation of cysteic acid residues (Scheme 10.41). The rupture of disulphide crosslinks, with attendant increase in urea-bisulphite and alkali solubility values, adversely affects fibre properties. As the severity of bleaching conditions increases, the urea-bisulphite solubility remains little changed but the relationships between alkali solubility and cysteic acid (Figure 10.36) and between cystine and cysteic acid (Figure... 

Figure 10.36 Relationship between alkali solubility and cysteic acid content of peroxide-bleached wool [259,261]...

As mentioned previously, additive treatments involve the application of a polymer to the fibre. This is usually prepared before application and contains reactive groups. However, it is also possible to form the polymer in situ within the fibres. The traditional approach is to apply the polymer after a subtractive oxidation treatment but environmental concern over A OX problems is increasing demand for additive treatments that can stand alone. There is no denying that the oxidative step can facilitate subsequent treatment with a polymer, since the scission of cystine disulphide bonds to yield cysteic acid residues provides useful reactive sites for crosslinking or anchoring the polymer. 

Figure 1.20 Cysteine and methionine are highly susceptible to oxidation reactions. Cysteine thiols can form disulfide linkages with other cysteine groups or be oxidized to cysteic acid. Methionine is oxidized very easily to the sulfoxide or sulfone products.

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