Sulfur-containing amino acids, and

The nonpolar amino acids (Figure 4.3a) include all those with alkyl chain R groups (alanine, valine, leucine, and isoleucine), as well as proline (with its unusual cyclic structure), methionine (one of the two sulfur-containing amino acids), and two aromatic amino acids, phenylalanine and tryptophan. Tryptophan is sometimes considered a borderline member of this group because it can interact favorably with water via the N-H moiety of the indole ring. Proline, strictly speaking, is not an amino acid but rather an a-imino acid. 

As a more sensitive detection method, MS can be very useful in amino acid determinations. For example, S-carboxymethyl-(R) cysteine or SCMC, is a mucolytic agent used in the treatment of respiratory diseases. The development of a method utilizing high performance IEC and atmospheric pressure ionization (API) mass spectrometry to quantify SCMC in plasma has been described.66 This method is simple (no derivatization needed), rapid (inn time 16 min.), sensitive (limit of quantification 200 ng/mL in human plasma), and has an overall throughput of more than 60 analyses per day. API-MS was used successfully with IEC to determine other sulfur-containing amino acids and their cyclic compounds in human urine.67 IEC has also been used as a cleanup step for amino acids prior to their derivatization and analysis by gas chromatography (GC), either alone or in conjunction with MS.68 69... 

Depending on diet and systemic (whole body) metabolism, which produces so-called fixed acids such as sulfate derived from sulfur-containing amino acids and phosphate, mainly from nucleic acid metabolism, there is a tendency for pH of body fluids to fall. 

Solouki, T. Emmet, M.R. Guan, S. Marshall, A.G. Detection, Number, and Sequence Location of Sulfur-Containing Amino Acids and Disulfide Bridges in Peptides by Ultrahigh-Resolution MALDI-FTICR Mass Spectrometry. Anal. Chem. 1997,69, 1163-1168. 

Marshall, A.G. Detection, Number, and Sequence Location of Sulfur-Containing Amino Acids and Disulfide Bridges in Peptides by Ultrahigh-Resolution... 

One particular area of concern is the feeding of protein to monogastric organic animals. In conventional production, current production relies on providing supplementary synthetic amino acids. Poultry has a high demand for sulfur-containing amino acids and pigs have a... 

Solouki, T., Emmett, M. R., Guan, S., and Marshall, A. G. (1997). Detection, number, and sequence location of sulfur-containing amino acids and disulfide bridges in peptides by ultrahigh-resolution MALDI FTICR mass spectrometry. Anal. Chem. 69,1163-1168. 

HRV Arnstein, N Artman, D Morris, EJ Toms. Sulfur-containing amino acids and peptide in the mycelium of Penicillium chrysogenum. Biochem J 76 353-357, 1960. 

Diammine- and Diamineplatinum Complexes with Non-Sulfur-Containing Amino Acids and Peptides... 

Duan, W., Roddick, F. A., Higgins, V. J., Rogers, P. J. (2004) A parallel analysis of H2S and SO2 formation by brewing yeast in response to sulfur-containing amino acids and ammonium ions. Journal of the American Society of Brewing Chemists, 62, 35 1. 

The existence of sulfite oxidase in plants snch as Arabidopsis thaliana (wall or thule cress), tobacco, pea, spinach, barley, carrot, and poplar trees has now been confirmed, and the enzyme from A. thaliana has been structurally characterized. The homodimeric, peroxisomal enzyme lacks the heme domain observed in animal sulfite oxidases, making it the simplest Mo-MPT enzyme yet isolated from eukarya. The animal and plant sulfite oxidases have an overall 47% sequence identity. The detoxification of sulfite, produced in the assimilation of sulfate into sulfur-containing amino acids and membrane components (sulfatides) and from environmental sources (acid rain), is also the principal role of the plant enzymes. 

The exact origin of thiazoles remains a mystery. They might form through the thermal degradation of cystine or cysteine (25, 26), or by the interaction of sulfur-containing amino acids and carbonyl compounds (27, 28). Thiazoles have been identified as volatile components of thermally degraded thiamine (29). 

The data in Figures 33 and 34 show typical thermodynamic properties (normal Marcus region) for the electron transfer reaction. In these examples, the rate of the process increases as the driving force of the reation (—AGet) increases. The properties observed in Figures 33 and 34 also predict the type of radical formed after electron transfer. From studies of sulfur-containing amino acids and sulfur-containing carboxylic acids [170-175] it is known that decarboxylation occurs only if the carbox-... 

These 3 sulfur-containing amino acids and their derivatives are susceptible to oxidation and other destructive reactions. Even when great care has been taken to remove all oxygen from hydrolysis tubes, considerable losses of cysteine and cystine are found after acid hydrolysis, and this usually prevents direct quantitation of these amino acids in proteins. However, total cysteine plus half-cystine content may be determined as cysteic acid after performic acid... 

Procedure Place 10 mg (ca. 0.04 0.08 mmole) of sulfur-containing amino acid and 10 mg of phenanthrene (as internal standard) in a 16 X 76 mm culture tube (screw cap with Teflon liner). Add 0.5 ml (ca. 2.6 mmoles) of BSA (or 0.5 ml ca. 3 mmoles, of BSTFA) and 1.5 ml of acetonitrile. Screw the cap on the tube and immerse just to the top of the liquid level in an oil bath at 150° for 5 minutes. Allow to cool and inject 5 JU.1 into the gas chromatograph. The chromatograms shown in Figs. 22 and 23 illustrate the results obtained by this procedure. The authors claim that the minimum detectable limit at a 2 1 signal-to-noise ratio with respect to the flame ionization detector is about 5 ng of sulfur-containing amino acid injected on the column. 

Foods high in sulfur-containing amino acids and whey protein may have a negative effect on the colonic mucosa in patients with ulcerative colitis (Parcell 2002). Sulfides that occur in protein fermentations may irritate the colonic mucosa, followed by epithelial cell damage and inflammation. 

Sulfur-containing amino acids and proteins form very strong soluble complexes with mercury 12, 50, 51). Humic acids are formed by partial decay of organic matter and may have sulfur-bearing residual proteins bound to quinoid polymers, thus acting as strong complexers of relatively... 

A review of the early 1970 s details the manganese compounds of sulfur-containing amino acids, and quotes evidence that cysteine (172 R = SH) and penicillamine bind via both the N and S donor atoms at higher pH values however, analysis of the papers quoted yielded little evidence for S binding. On the other hand, there is sound evidence that when the thiol group is methylated, as in 5-methylcysteine and methionine (172 R = SMe and CHjSMe respectively), the S does not coordinate, either in solution or in the solid state. ... 

Meat flavor is due to a great number of volatiles from different chemical classes. However, most of the odorants described as meaty aroma contain sulfur. The two most important reactions which generate meaty aroma compounds are the reactions between sulfur containing amino acids and reducing sugars (Maillard reaction) and the thermal degradation of thiamin [35], Sulfur-containing furans are the basic chemicals responsible for the aroma of thermally treated meat. 

Asparagus has a lot of sulfur-containing amino acids, and when you urinate after eating this vegetable, the sulfur can be smelled in your waste. 

The chiroptical properties of chromophoric derivatives of optically active thiols (including sulfur-containing amino acids and peptides) have been reviewed (Toniolo, 1973). 

Kudzin, Z.H. Saganiak, M. Kot3mski, A. Ciesielski, W. Comparison of the thin-layer chromatographic properties of sulfur-containing amino acids and their aminophosphonic analogues. J. Chromatogr. A, 2000, 888, 335-339. 

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