Cysteine structural formula

Consider the cysteine molecule shown in Table 23.3. Write structural formulas for... 

Therapeutic Function Antirheumatic, Immunomodulator Chemical Name L-Cysteine, N-(2-mercapto-2-methyl-l-oxopropyl)-Common Name Bucillamine Tiobutarit Structural Formula ... 

We have devised a DvMF model by substituting a methyl group for cysteine (Cys) in the structural formula shown in Figure 9-15, where SI is the bridging atom between the Fe atom and Ni atom, S2 is one of the bridging S atomsof the cysteine amino acids and S3 is one of the S atoms of the cysteine amino acids coordinated to the Ni atom only. We then optimized the structure. The optimized atomic distances and... 

Cystine is an amino acid formed from the oxidation of two cysteine molecules to form a disulfide bond. The molecular formula of cystine is C6H12O4N2S2. Draw the structural formula of cystine. Hint For the structure of cysteine, see page 385.)... 

Write a complete structural formula and an abbreviated formula for the tripeptide formed from aspartate, cysteine, and valine in which the C-terminal residue is cysteine and the N-terminal residue is valine. 

Structural formulae and yields of the cysteinyldopa adducts formed in the first stage of the co-oxidation of dopa and cysteine in the presence of tyrosinase.12... 

Accordingly, as the first step, the interaction of qinghaosu and cysteine in the presence of a catalytic amount of Fe(lFlll) was studied. From the reaction mixture, a water-soluble compound was isolated. This compound could be visualized with ninhydrin on TLC, and it showed a formula of C16H27NO6S H2O. Treatment of this compound with acetic anhydride yielded a cyclic thioether 165, which in turn undoubtedly showed the formation of adduct 166 of 1 and cysteine through a a bond between C-3 and sulfur. A stable adduct 167 of cysteine and 170 was then isolated in 33% yield with the same reaction protocol. As mentioned, both adducts of cysteine with primary and secondary free radical derived from arte-mether were also identified recently, albeit in low yield (Structure 5-25). More... 

This structure, although consistent with many facts, did not explain the peculiar properties of the A-terminal isoleucine and the negative test for —SH groups. Further experiments led to the conclusion that a thiazoline ring is formed between isoleucine and cysteine this was later proved to be correct. All these results led to the formula for bacitracin A which is now generally accepted - Figure 1.4). 

Fig. (6). Reaction mechanism observed during reaction of HEL and L-cysteine. The 3D-model shows the transition structure obtained by energy minimisation of the cysteine thiolate anion and a molecule of helenalin using the semiempirical AMI hamiltonian. The surface representation of the highest occupied molecular orbital (HOMO) shows that this structure corresponds to the middle formula (above) in which the major part of the jt-electron density is transferred to the 11-.12 bond. Note the proximity of the NH3T to the lactone carbonyl oxygen.

S-Donor ligands. Cysteine complexes of formula [PML2] (M = Pd or Pt) have been prepared by treating K2[MCl4] with excess cysteine hydrochloride. Their i.r. spectra confirm co-ordination ina S and O sites, with free amine groups. Similarly the P-ketosulphoxide complex [PdL2] (L = PhCOCH2SOMe) has been shown to have the structure (54 M = Pd). ° In an extension of previous... 

Several L-cysteine derivatives carry alkyl or related substituents at the S-atom. They occur at the oxidation level of sulfides or of sulfoxides (alliins. Table 46). The substances are aliphatic or have a cyclic structure, like cycloalliin. Several products are dimeres, cf. the formula of djenkolic acid. 

The side chains of proteins can undergo post-translational modification in the course of thermal processes. The reaction can also result in the formation of protein cross-links. A known reaction which mainly proceeds in the absence of carbohydrates, for example, is the formation of dehydroalanine from serine, cysteine or serine phosphate by the elimination of H2O, H2S or phosphate. The dehydroalanine can then lead to protein cross-links with the nucleophilic side chains of lysine or cysteine (cf. 1.4.4.11). In the presence of carbohydrates or their degradation products, especially the side chains of lysine and arginine are subject to modification, which is accompanied by a reduction in the nutritional value of the proteins. The structures of important lysine modifications are summarized in Formula 4.95. The best known compounds are the Amadori product -fructoselysine and furosine, which can be formed from the former compound via the intermediate 4-deoxyosone (Formula 4.96). To detect of the extent of heat treatment, e. g., in the case of heat treated milk products, furosine is released by acid hydrolysis of the proteins and quantitatively determined by amino acid analysis. In this process, all the intermediates which lead to furosine are degraded and an unknown portion of already existing furosine is destroyed. Therefore, the hydrolysis must occur under standardized conditions or preferably by using enzymes. Examples showing the concentrations of furosine in food are presented in Table 4.13. 

The amino acid cysteine plays an important role in the three-dimensional structure of proteins by forming disulfide bridges. The percent composition of cysteine is 29.74 percent C, 5.82 percent H, 26.41 percent 0,11.56 percent N, and 26.47 percent S. What is the molecular formula if its molar mass is approximately... 

Phalloidin is one of the poisons of the mushroom Amanita phaUoides with great toxicity. Only 50 pg are lethal for a mouse. Seven different amino acids are involved in its structure including such unusual hydroxy amino acids as hydroxy-leucine and allothreonine (T. Wieland). There is a bridge between tryptophan and the SH group of cysteine which yields hydroxy tryptophan upon hydrolysis. The formula is not reproduced here. 

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