1.
Why proteins evolve at different rates: the functional hypothesis versus the mistranslation-induced protein misfolding hypothesis.
Park, D, Choi, SS
FEBS letters. 2009;(7):1053-9
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Abstract
Protein evolutionary rates have been presumed to be mostly determined by the density of functionally important amino acids in a given protein. They have been shown to correlate with variables intuitively related to functional importance of proteins, such as protein dispensability and protein-protein interactions. Surprisingly, the best correlate of the evolutionary rates has turned out to be not the functional importance of a protein, but the expression level of the protein. Drummond and Wilke suggest that the dominant role of expression levels in slowing the rate of protein evolution stems from a selection pressure against mistranslation-induced protein misfolding. We will review current evidence for and against different hypotheses on determining evolutionary rates.
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Biomarkers for oxidative stress status of DNA, lipids, and proteins in vitro and in vivo cancer research.
Hwang, ES, Kim, GH
Toxicology. 2007;(1-2):1-10
Abstract
Oxidation and the production of free radicals are an integral part of human metabolism, and oxidative stress is related to many diseases, including cancer and heart disease. The use of biomarkers for oxidative stress may provide further evidence of a causal relationship between oxidative damage to macromolecules (DNA, lipids, and proteins) and cancer. A wide variety of functional assays, both in vivo and ex vivo, include various measures of DNA oxidation (oxidized DNA bases such as 8-OHdG, autoantibodies to oxidized DNA, modified comet assay), lipid oxidation (thiobarbituric acid-reactive substances, exhaled pentane/ethane, low-density lipoprotein resistance to oxidation, isoprostanes), and protein oxidation (protein carbonyls). The objective of this review is to discuss characteristics and methodologic issues for studies involving biomarkers of exposure to antioxidant nutrients and of oxidative stress status. This paper provides an overview on the current knowledge of oxidative DNA, lipid, and protein damage and cancer incidence.