Liver chemical modifications

Konishi, K., and Fujioka, M. (1987) Chemical modification of a functional arginine residue of rat liver glycine methyltransferase. Biochemistry 26, 8496-8502. 

In spite of the improved stability to nucleases, achieved through chemical modification, AS-ODN degradation in plasma still occurs, predominantly from the 3 -terminus. In the liver and kidney, the major sites of metabolism, AS-ODNs are degraded from the 5 -terminus as well [127,128]. 

Although the antibacterial spectrum is similar for many of the sulfas, chemical modifications of the parent molecule have produced compounds with a variety of absorption, metabolism, tissue distribution, and excretion characteristics. Administration is typically oral or by injection. When absorbed, they tend to distribute widely in the body, be metabolized by the liver, and excreted in the urine. Toxic reactions or untoward side effects have been characterized as blood dyscrasias crystal deposition in the kidneys, especially with insufficient urinary output and allergic sensitization. Selection of organisms resistant to the sulfonamides has been observed, but has not been correlated with cross-resistance to other antibiotic families (see Antibacterial AGENTS, SYNTHETIC-SULFONAMIDES). 

Detoxification of dietary alleochemicals, which can be achieved by symbiotic bacteria or protozoa living in the rumen or intestines, or by liver enzymes which are specialized for the chemical modification of xenobiot-ics. This evolutionary trait is very helpful for Homo sapiens, since it endowed us with a means to cope with our man-made chemicals which pollute the environment. Carnivorous animals, such as cats, are known to be much more sensitive toward plant poisons (505). It was suggested that these animals, which do not face the problem of toxic food normally, are thus not adapted to the handling of allelochemicals. 

Elimination Filtration and secretion in the kidneys chemical modification in the liver... 

Quandt L and Huth W (1984) Modulation of rat-liver mitochondrial acetyl-CoA acetyl-transferase activity by a reversible chemical modification with coenzyme A. Biochim-ica et BiophysicaActa 784,168-76. 

Several cytidylyltransferases were shown to be inhibited by CMP and CDP [582]. The observation that 2 -CMP, 3 -CMP and 2, 3 -cyclic CMP do not inhibit shows that the phosphate residue at the 5 position of ribose is required for inhibition. These studies also demonstrate that the ribose moiety must be intact for inhibition and that chemical modifications of the cytidine residue tested do not lead to inhibitors. An inhibitory effect of the methyl (3-glycoside and the 4-oxo-derivative of Neu5 Ac on the cytidylyltransferase from rat liver was described [408]. 

Neither bacteria nor cultured mammalian cells reflect the complexity of whole animals since they lack the inherent biochemical properties of the liver (oxidations and other chemical modifications carried... 

Compounds that cannot be oxidized as fuels in the human are often excreted in the urine. Chemical modifications often occur in the liver, kidney, or other tissues that inactivate or detoxify the chemicals, make them more water-soluble, or otherwise target such molecules for excretion. Uric acid, the basis of Lotta Topaigne s pain, is excreted in the urine (see Fig. 5.26). Judging from the similarity in structure, do you think it is derived from the degradation of purines, pyrimidines, or pyridines ... 

Vercauteren, R., Schacht, E. and Duncan, R. (1992) Effect of the chemical modification of dextran on the degradation by rat liver lysosomal enzymes. J. Bioact. Biocomp. Polym. 7 346-357. 

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