Protein alteration

Transitions occur constantly in nature molecules change from one tautomeric form to another, radioactive nuclei decay to form other nuclei, acids dissociate, proteins alter their shapes, molecules undergo transitions between electronic states, chemicals react to form new species, and so forth. Transition rules allow the simulation of these changes. 

Isoelectric focusing of transferrin is a useful biochemical test for assisting in the diagnosis of these conditions truncation of the oligosaccharide chains of this protein alters its isolectric focusing pattern... 

Because of the relative ease with which they can be obtained, plasma proteins have been smdied extensively in both humans and animals. Considerable information is available about the biosynthesis, turnover, strucmre, and functions of the major plasma proteins. Alterations of their amounts and of their metabolism in many disease states have also been investigated. In recent years, many of the genes for plasma proteins have been cloned and their stmcmres determined. 

Second, the reactive species of a xenobiotic may bind to a protein, altering its antigenicity. The xenobiotic is said to act as a hapten, ie, a small molecule that by itself does not stimulate antibody synthesis but will combine with antibody once formed. The resulting antibodies can then damage the cell by several immunologic mechanisms that grossly perturb normal cellular biochemical processes. 

Witzmann FA et al. Toxicity of chemical mixtures proteomic analysis of persisting liver and kidney protein alterations induced by repeated exposure of rats to... 

Witzmann FA et al. Regional protein alterations in rat kidneys induced by lead exposure. Electrophoresis 1999 20 943-951. 

Because phosphate groups are negatively charged, phosphorylation of a protein alters its charge, which can then alter the conformation of the protein and ultimately its functional activity. A change in the state of protein phosphorylation can be achieved physiologically through increases or decreases in the activity of either protein kinases or protein phosphatases. Examples of each of these mechanisms occur in the nervous system, often in concert with one another, to elicit complex temporal patterns of protein phosphorylation. 

Mallucci, G. R. et al. Post-natal knockout of prion protein alters hippocampal CA1 properties, but does not result in neurodegeneration. EMBO J. 21 202-210,2002. 

An X-ray crystal structure of 28 bound in the thumb-region of the NS5B polymerase showed little interaction of the acetamide moiety with the protein. Alterations at this position were explored in order to improve the physical properties of the compound. Incorporation of basic amines as part of this side-chain, leading to zwitterionic compounds, reduces plasma binding and has a beneficial effect on cell activity and pharmacokinetic profiles. In the cell-based replicon assay, racemic 29 has an EC50 of 152 nM in the presence of 10% fetal calf serum and 376 nM in the presence of 50% normal human serum [71],... 

Observations that the presence of protein affects the colour change of some indicators used in acid-base titrations led to the development of methods for the quantitation of proteins based on these altered absorption characteristics of such dyes. As the presence of protein alters the colour produced by these indicators when measuring pH, so in the quantitation of proteins using dye-binding methods the control of pH is vital. 

Khanuja PS, Lehr JE, Soule HD, Gehani SK, Noto AC, Choudhury S, Chen R, Pienta KJ (1993) Nuclear matrix proteins in normal and breast cancer cells. Cancer Res 53(14) 3394-3398 Konety BR, Nangia AK, Nguyen T.S, Veitmeier BN, Dhir R, Acierno JS, Becich MJ, Hrebinko RL, Getzenberg RH (1998) Identification of nuclear matrix protein alterations associated with renal cell carcinoma. J Urol 159(4) 1359-1363... 

Bowman ZS, Morrow JD, JoIIow, DJ, et al. Primaquine induced hemolytic anaemia role of membrane lipid peroxidation and cytoskeletal protein alterations in the hemotoxicity of 5-hydroxyprimaquine. J Pharmacol Exp Ther 2005 314 838-845. 

Why does the reaction catalyzed by the dnaB gene product require ATP hydrolysis Does this protein alter the linking number of DNA Explain. 

Only a small percentage ( 3%) of a protein sample is labelled via fluorescent dye, and this addition to each protein alters the molecular mass by approximately 580 Da. In proteins over 30 kDa, this will not significantly alter the position where they resolve by 2DE. However, in smaller proteins this will significantly adjust positioning compared to the unlabelled proteins, but post-electrophoresis staining with a conventional stain allows further analysis. To date, a DIGE analysis of parasite proteins has not been published. 

Much of the cell is composed of protein, and its enzymes are protein. Alteration of the protein is referred to as denaturation. In denaturation, hydrogen and disulfide... 

These are metabolites that bind primarily to the parent enzyme. This category includes substrates that form enzyme-bound intermediates that react with the active site of the enzyme. Such chemicals are known as suicide substrates. A number of compounds are known to react in this manner with CYP, and such compounds are often used experimentally as CYP inhibitors (see the discussion of piperonyl butoxide, Section 7.2.2). Other compounds, although not true suicide substrates, produce reactive metabolites that bind primarily to the activating enzyme or adjacent proteins altering the function of the protein. 

The nature of protein in the diet also appears to alter xenobiotic metabolism. Clinton and Visek ( / and Clinton and Visek (Zi.) observed that protein alters carcinogen metabolism and that fat level in the diet alters the absorption and distribution of DMBA in the tissue. The effects of protein nutriture also are observed when 1, 2-dimethylhydrazine is included in the diet. It appears that inadequate protein in the diet causes a significant decrease in hepatic MFO activity. 

As previously mentioned, carcinogenesis is a complex process and it would be naive to believe that dietary protein alters only the initiation phase. A series of eloquent studies by Appleton and Campbell (22, 23, 24) have indicated that the effects exerted by dietary protein during the promotional phase of AFBi hepatocar-cinogenesis are as important, if not more so, than the effects seen during the initiation phase. 

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