Protein amino acids, toxic proteins

These amino acid and protein binding results might account for the low toxic side effects of this class of anticancer agents (72). On the other hand, the relatively weak binding to amino acids and proteins could perhaps aid in transport and delivery of active species to cancer cells prior to binding to DNA or RNA (75). 

Kataoka (1997) describes a method for the analysis of 21 protein amino acids and 33 nonprotein amino acids with NPD detection. One disadvantage of this method is the use of diazomethane, which is explosive and toxic (Kataoka, 1997). A method for homocysteine with GC-FID analysis uses a one-step derivatization with ethyl chloroformate and an extraction procedure (Husek et al., 2003). 

L-Canavanine, another non-protein amino acid, occurs in high concentrations in the tropical vine Dioclea megacarpa (sea purse, a legume) and is very toxic to mice. Its structure is NH2C(NH2)=N0(CH2)2CH(NH2)C02H. This is very similar to arginine, with which it interferes. 

There seems to be a critical level of cadmium in the kidney when the kidney metallothionein is saturated and the free cadmium causes toxicity. The damage to the kidney occurs in the first and second segments of the proximal tubule. This can be detected biochemically as glucose, amino acids, and protein in urine. The proteins are predominantly of... 

Final cleavage of the peptide from the support requires HF or other acids of high ionizing power (TfOH, HBr/AcOH [18]). HF is a good solvent for amino acids and proteins, and does not usually lead to the cleavage of peptide bonds [23], Because of its toxicity and capacity to dissolve glass, HF must be handled with great care in special HF-resistant containers. 

A compound that is able to influence the relaxation times of water protons has to be paramagnetic. In the Periodic System paramagnetic ions are to be found amongst the transition metals and the rare earth metals (lanthanides). However, it was well known, that the free ions of heavy metals are toxic. Lanthanide ions form soluble complexes with ligands such as phospholipids, amino acids and proteins that are present in plasma. The liver and the skeleton are the major sites of accumulation of free metal ions. Uptake in the liver is mediated by the hepa-tocytes [2]. 

Within cells, sulfur mustard forms adducts with DNA, primarily those described in Toxicity of sulfur mustard, above. Adducts can also be formed with nucleophilic sites of amino acids and proteins. Contrary to DNA adducts, there is no specific mechanism to reverse protein adduct formation. For this reason, there is a strong forensic interest in the detection of protein adducts of sulfur mustard as these may provide evidence of sulfur mustard exposure for prolonged periods after the incident. 

Non-protein amino acids (NPAAs) are especially abundant in the family Fabaceae, but are also present in several monocots (families Alliaceae, Iri-daceae, Liliaceae), Gucurbitaceae, Euphorbiaceae, Resedaceae, Sapindaceae and Gycadaceae. NPAAs are also toxic components of some fungi (e.g. coprine... 

Nutritional Antagonisms. Some plants possess the capability to present a nutritionally undesirable diet to pests apart from their biosynthesis (or failure to biosynthesize) of allelochemlcals. Rosenthal (33) and Dahlman and Berge (34) have shown that L-Canavanine, a non-protein amino acid of certain leguminous plants is Incorporated into proteins of some insects with toxic results. The tobacco hornworm is sensitive to the formed protein, however the tobacco budworm, Hellothls vlrescens (Fab.) and the bruchld beetle Caryedes brasillensls are able to tolerate and... 

Crystals from selenium-methionine- and/ or selenium-cysteine-labeled proteins can be studied by multi-wavelength anomalous dispersion (MAD) phasing techniques that can facilitate the solution of an X-ray crystal structure from a single crystal form [11]. However, if in vivo expression systems are used to prepare selenium-labeled proteins, amino acid metabolism and the toxicity of Se-methionine can result in low protein yields and low incorporation rates. 

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