8- -i.-cysteine

From this, it is clear that D-glyceraldehyde is (i )-glyceraldehyde, and L-alanine is (S)-alanine (see figure). Interestingly, the u-car-bon configuration of all the L-amino acids except for cysteine , (S). Cysteine, by virtue of its thiol group, is in fact (i )-cysteine. 

Figure 30-8. Catabolism of i-cysteine via the cysteine sulfinate pathway (top) and by the 3-mercaptopy-ruvate pathway (bottom).

These workers have developed another new type of chiral S/N ligands, namely aziridine sulfides, which were easily synthesised in a straightforward synthetic route from inexpensive and readily available (i )-cysteine. The efficiency of this sterically and electronically varied set of ligands was then examined as chiral catalysts in the palladium-catalysed test reaction. The alkylated product was obtained in excellent yields and stereoselectivities of up to 99% ee, as shown in Scheme 1.44. 

According to a Macherey-Nagel application note [35], a mixture of 20 ng each of (i)-cysteine, (L)-glutathione, and (L)-penicillamine was resolved in less than 12 min by HPLC. The method used a Nucleosil 100-5SA column (15 cm x 4.6 mm i.d.) with aqueous 4.5 g/L ammonium citrate-6 g/L phosphoric acid at pH 2.2 as the mobile phase (eluted at 1 mL/min) and electrochemical detection at a gold electrode polarized at +800 mV. 

The rate of NO formation in the reaction between I-Cysteine (i-Cys) and a fixed amount of Ipramidil increased as the I-Cys /furoxan ratio increased and became constant for ratios above 50 1. A reasonable mechanism to justify their findings has been proposed (Scheme 6.8). 

I. Y. Hwang, A. A. Elfarra, Cysteine S-Conjugates May Act as Kidney-Selective Prodrugs Formation of 6-Mercaptopurine by the Renal Metabolism of, V-(6-Purinyl)-i,-cysteine , J. Pharmacol. Exp. Ther. 1989, 251, 448 - 454. 

CASRN 133-06-2 molecular formula C9H8CI3NO2S3 FW 300.57 Biological. In water, captan reacted with the fungicide i-cysteine forming a compound with an absorption maximum of 272 mm which was identified as 2-thiazolidinethione-4-carboxylic acid. In addition, tetrahydrophthalimide also formed (Lukens and Sisler, 1958). 

I Brand Name(s) Acetadote, Mucomyst Chemical Class Amino acid, i-cysteine... 

A-Palmitoyl-S-f2,3-bis(palniitoyloxy)-(2/ ,.9)-propyl]-(i )-cysteine ferf-Butyl Ester, Plm-Dhc(Plm)2-OtBu 90 ... 

Urinary metabolites are S-methylthioacetic acid sulfoxide, V-acetyl-.S -methyl-L-cysteine and /-(methylthioacetyl)glycine, which are metabolites of Y-methyl-i-cysteine and 5-methylglutathione. These last two compounds were found after incubation of methyl chloride with rodent liver, kidney and brain homogenates. The methyl group of methyl chloride is metabolized via -methyl-L-cysteine to formate which is found in urine and blood of rats, whereas formaldehyde is found in rat liver microsomes and blood of mice and rabbits (lARC, 1986). 

Trichloroethane is rapidly absorbed after inhalation, oral administration and application to the skin in rodents. 1,1,2-Trichloroethane is extensively metabolized in mice given 100-200 mg/kg bw by intraperitoneal injection, 73-87 % of the dose being eliminated in the urine and 16-22% in expired air. Several urinary metabolites have been identified chloroacetic acid, S-carboxymethyl-i,-cysteine, thiodiacetic acid, 2,2-dichloroethanol and oxalic acid (lARC, 1991). 

Patel, N., Bimer, G, Dekant, W. Anders, M.W. (1994) Glutathione-dependent biosynthesis and bioactivation of, S -(l,2-dichlorovinyl)glutathionc and. S -(1,2-dichlorovinyl)-i,-cysteine, the glutathione and cysteine S-conjugates of dichloroacetylene, in rat tissues and subcellular fractions. Drug Metab. Dispos., 22, 143-147... 

Isoleucine Arginineb Leucine Arginine i Cysteine Asparagine... 

On the contrary, Nakanishi et al. [34] reported that mucin layer works as a barrier to the increased absorption of sulfanilic acid, a nonabsorbable drug and noninteracted drug with CyDs, by (3-CyD because enhanced absorption of sulfanilic acid from the rat rectum was not induced by (3-CyD even with pretreatment with TV-acetyl-i-cysteine (NAQ, sodium deoxy-cholate (NaDC), or sodium lauryl sulfate (SLS). Thus, (3-CyD may have a moderate absorption-enhancing effect in rectum. 

LC/MS/MS is an important technique for the analysis of free metabolites and covalent adducts of sulfur mustard in urine and blood. In the case of TDG and TDGO, LC/MS has not yet been able to achieve the LODs obtainable with GC/MS after derivatization. LC/MS/MS has, however, been used successfully to analyze the metabolites (20, 21) derived from an initial reaction of sulfur mustard with glutathione (see Chapter 16). The two metabolites (20), derived from the 3-lyase pathway, can be isolated from urine by SPE on a hydroxylated polystyrene-divinylbenzene polymeric cartridge. Using a sensitive triple sector quadrupole LC/MS/MS system, detection limits of O.lng/ml have been achieved using positive ESI and MRM (56). This provides a useful alternative to GC/MS/MS, which requires reduction of the sulfoxide functions with titanium trichloride. An LC/MS/MS method (detection limit lng/ml) has been developed for the analysis of the hisf N - ace ly I cysteine) metabolite (21) in urine (57). Concentration from acidified urine was achieved on... 

Biirgi and co-workers [154-156] have reported a series of conformational investigations of chiral ligands absorbed on AuNPs using VCD spectroscopy complemented with DFT calculations, a powerful spectroscopic tool for conformational studies of condensed matters. Three organic chiral molecules, namely /V-acetyl-cysteine, /V- isobutyry I -cysteine, and l,l -binaphthyl-2,2 -dithiol (BINAS), were used as chiral ligands in their studies. The details about how to prepare monolayer-protected AuNPs with these ligands can be found in the pertinent references [154-156]. The measured VA and VCD spectra of the AuPNs protected by /V-isobutyryl-L/D-cysteine monolayer are shown in Fig. 18, as examples. As one... 

C=0 bonds in the trans arrangement. These authors therefore concluded that conformation a is the preferred orientation for /V-isobutyryl-i,-cysteine to attach to AuNPs in which the chiral ligand interacts with the AuNPs through the carboxylate and the sulfur atoms. These pioneering studies demonstrate the great potential of VCD spectroscopy for providing insight into the conformations of chiral molecules adsorbed on small metal particles. 

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