D-cysteine

D-cysteine (derivatives) 3-chloro-DL-alanine + iNaHS 3-chloro-D-Ala dehydrochlorinase or Pseudomonas putidaE. coli etc ... 

Protected 3-methyl-D-cystein (257 Scheme 3.94), a structural unit of the peptide antibiotics nisin and subtilin, has been synthesized through the ring-opening of the aziridinecarbamide 254 with thiobenzoic acid (255) [143, 144]. The reaction took place overnight at room temperature and in methylene chloride to give 256 in greater than 95% yield. 

Nagasawa T, T Ishii, H Kumagai, H Yamada (1985) D-Cysteine desulfhydrase of Escherichia coli. Eur J Biochem 153 541-551. 

Scheme 3.13 D-Cysteine-derived aziridine disulfide ligands for additions of ZnEt2 to aldehydes.

Enantioselectivities ranging from 18 to 94% ee were obtained by Martens et al. by using C2-symmetric bis-p-amino alcohols derived from D-cysteine for the enantioselective addition of ZnEt2 to benzaldehyde (Scheme 3.27). ... 

Scheme 3.27 D-Cysteine-derived C2-symmetric bis-P-amino alcohol ligands for addition of ZnEt2 to benzaldehyde.

Scheme 10.61 Borane reduction of acetophenone with D-cysteine-derived bis-P-amino alcohol ligands.

Figure 1.15 AdsorptionofcysteineonAu l 1 0. Molecular model shows the deprotonated thiolate surface species, (a) Model of the reconstructed (1 x 2)-Au l 1 0 surface (b-d) show, respectively, dimers of L-cysteine, D-cysteine, and the two together characteristically rotated relative to the (1 1 0) azimuth. (Adapted with permission from Ref. [57], Copyright 2002, Macmillan Publishers Ltd.)...

The nitrone 394, prepared from -hy droxytry p tarn i ne 392 and A -BOC- -methyl-D-cysteine 393 <2000JCS(P1)4570>, was treated with trifluoroacetic acid at room temperature to yield the corresponding tetracycle 47 along with the tetrahydro-P-carboline (Scheme 86) <2000J(P1)3487>. 

FIGURE 6.7 CVs obtained at (a, b) Cu,Zn-SOD/cysteine-modified, (c) bare, and (d) cysteine-modified Au electrodes in 25 mM PBS (pH 7.4) saturated by N2 (a, c, d) or 02 (b). Solutions (b) and (c) contain 0.002U ml-1 XOD and 25mM xanthine. Potential scan rate, lOOmV s. (Reprinted from [150], with permission from the Royal Society of Chemistry.)... 

With isotopes it has been possible to show that all enzyme-catalyzed reactions are stereospecific. Before the availability of isotopes, there was no way of testing this generalization. Of course there are some apparent exceptions to prove the rule. Bently has listed a considerable number (2>, Table XIII, Chapter 6). The most interesting one to me seems to be luciferase, but that is an exception that isn t an exception. Thus, the enzyme luciferase acts on its substrate luciferin (2), in the presence of ATP and O2, to oxidize the luciferin to oxyluciferin (3). The reaction consists of an initial activation of the substrate by ATP to give luciferyl adenylate, after which the oxidation takes place. When the natural enantiomer (synthesized from D-cysteine) is activated and oxidized, light is emitted. The other enantiomer is also acted on by the enzyme, and is converted to the adenylate, but oxyluciferin is not formed, and there is no bioluminescence 37,38,38a)... 

ESl-MS of cysteine solutions yields only the singly protonated hexamer [(Cys)6-H]. No preference for the chirality of the individual aminoacidic components is observed." Addition of cysteine to a serine solution yields abundant homochiral mixed octamer [(L-Ser)g m(L-Cys) -H] (m = 0-2). No [(L-Ser)g. (D-Cys)m H]+ (m = 1,2) octamers, but only [(L-Ser)g-H]+ are observed by using the wrong D-cysteine enantiomer. A similar picture is observed by replacing cysteine with other aminoacid, such as aspartic acid, asparagine, leucine, and methionine. 

OPA in combination with chiral thiols is one method used to determine amino acid enantiomers. A highly fluorescent diastereomeric isoindole is formed and can be separated on a reverse-phase column. Some of these chiral thiols include N-acetyl-L-cysteine (NAC), N-tert-butyloxy-carbonyl- L-cysteine (Boc-L-Cys), N-isobutyryl- L-cysteine (IBLC), and N-isobutyryl- D -cysteine (IBDC). Replacing OPA-IBLC with OPA-IBDC causes a reversal in the elution order of the derivatives of D- and L-amino acids on an ODS column (Hamase et al., 2002). Nimura and colleagues (2003) developed a novel, optically active thiol compound, N-(tert-butylthiocarbamoyl)- L-cysteine ethyl ester (BTCC). This reagent was applied to the measurement of D-Asp with a detection limit of approximately 1 pmol, even in the presence of large quantities of L-ASP. 

Figure 2 Selected stmctures of select host defense peptides representing the major structural classes (a) /3-sheet class (HNP-3 PDB1DFN) (b) linear a-helical class (magainin PDB2MAG) (c) extended class (indolicidin 1G89) (d) cysteine-stabilized 0-/3 (protegrin-3 1PFP). All stmctures were made with MOLMol and the color schema are as follows red/yellow, o-helical propensity aqua, /3-sheet propensity gray, extended or coil.

The posttranslationally modified cross-link S -[(Z)-2-aminovinyl]-D-cysteine (AviCys Figure 1) has been found at the C-terminus of the lantibiotics epidermin, gallidermin, cypemycin, and mutacin III. A group of decarboxylases, called LanD proteins, are encoded in the lantibiotic gene clusters and are responsible for this modification. The first LanD protein characterized was EpiD from the epidermin-producing strain S. epidermis EpiA and EpiD were separately overexpressed in E. coliand purified. 

This enzyme [EC 4.4.1.15] catalyzes the hydrolysis of D-cysteine to produce pyruvate, ammonia, and H2S. 

Growth experiment of S-carboxymethyl-D-cysteine(D-SCMC) in a DL-SCMC supersaturated solution were carried out by a batchwise agitated crystallizer and the growth rates in longitudinal and lateral directions and optical purity of D-SCMC crystal were measured. 

Cysteine, HS-CH2-CH(NH2)-COOH, binds covalently to gold due to the thiol group. When depositing enantiomeric pure (L-cysteine or D-cysteine) on Au( 110) at... 

The sulfur extrusion method 21 has been extensively investigated for the synthesis of threo-3-methyllanthionine 25 however, in this case desulfurization was not used to generate the amino acid (either in free or protected form), but rather to form different sulfide-bridged cyclic peptides as precursors for the total synthesis of nisin (3). Development of synthetic methods in this area was particularly important in respect to the synthesis of nisin, since this lantibiotic contains four // eo-3-methyllanthionine residues. The synthesis proceeded from a protected f/zreo-3-methyl-D-cysteine in the N-terminal position and L-cysteine in the C-terminal position. 

The synthesis of four out of eight possible stereoisomers of 3-methyllanthionine [(25,35,67 ), (25,37 ,67 ), (25,35,65), (25,37 ,65)] has been achieved using the reaction of Z-protected 3-methyl-D-cysteine with d- or L-3-chloroalanine in yields of 35—53% J64 The methyl-D-cys-teine stereoisomers were obtained by two routes. Firstly from (25,35)-threonine via O-tosylation and subsequent inversion of configuration by nucleophilic attack with thiobenzoic acid. The resulting derivative was debenzoylated and oxidized to the respective cystine derivative prior to the reduction with Zn/HCl to give the eryt/u-o-3-methyl-D-cysteine... 

S,3R). Secondly, the t/treo-3-methyl-D-cysteine (25,35) was prepared using the previously described addition of thiocarboxylic acid to threonine-derived aziridines. 62 ... 

Despite the known propensity for racemization, base-catalyzed cyclization continues to be used occasionally. Thus a series of cyclodipeptides derived from 1-methyl-L- and D-tryptophans and S-methyl-L-and D-cysteine have been prepared by ammonia-catalyzed cyclization (87JMC1706), (Scheme 1). 

---