0000000000206800
AUTHOR
Helmut Sies
The major isozyme of rat cardiac glutathione transferases. Its correspondence to hepatic transferase X.
1. A major isozyme of rat heart glutathione transferase was purified to homogeneity by Sephadex G-200 gel filtration, ammonium sulfate precipitation, CM-cellulose chromatography and affinity chromatography on S-hexylglutathione-linked Sepharose 6B. 2. The purified isozyme was a dimer with an apparent relative molecular mass of 50000 composed of two Yb-size subunits (Mr= 26 500). The isozyme is immunologically related to rat liver glutathione transferase X and 3–3, especially closely to transferase X, and no immunological cross-reactivity with subunits 1 and 2 of hepatic glutathione transferases was observed. The isoelectric point (pI = 6.9) of the isozyme was identical with and the substrat…
DNA damage by peroxynitrite characterized with DNA repair enzymes.
The DNA damage induced by peroxynitrite in isolated bacteriophage PM2 DNA was characterized by means of several repair enzymes with defined substrate specificities. Similar results were obtained with peroxynitrite itself and with 3-morpholinosydnonimine (SIN-1), a compound generating the precursors of peroxynitrite, nitric oxide and superoxide. A high number of base modifications sensitive to Fpg protein which, according to HPLC analysis, were mostly 8-hydroxyguanine residues, and half as many single-strand breaks were observed, while the numbers of oxidized pyrimidines (sensitive to endonuclease III) and of sites of base loss (sensitive to exonuclease III or T4 endonuclease V) were relativ…
Nitric oxide-mediated inhibition of androgen receptor activity: possible implications for prostate cancer progression.
Chronic inflammation increases the risk of cancer and many cancers, including prostate cancer, arise at sites of chronic inflammation. Inducible nitric oxide synthase (iNOS) is an enzyme dominantly expressed during inflammatory reactions. Although synthesis of high amounts of nitric oxide (NO) by iNOS has been demonstrated in pathophysiological processes, such as acute or chronic inflammation, autoimmune diseases or tumorigenesis, the role of iNOS activity in most of these diseases is poorly understood. Analysing prostate cancer biopsies by immunohistochemistry we found iNOS protein expression in tumor cells strongly paralleled by nitrotyrosine suggesting that iNOS is fully active. In vitro…
[33] Use of repair endonucleases to assess DNA damage by peroxynitrite
Publisher Summary This chapter discusses the use of repair endonucleases to assess DNA damage by peroxynitrite. Repair endonucleases allow a convenient quantification of various types of oxidative modifications induced by peroxynitrite, both in cultured cells and in cell-free DNA. The high sensitivity of the assays allows highly ectotoxic exposure conditions to be avoided—as well as the generation of secondary DNA modifications—that often become a problem at high levels of damage because primary DNA oxidation products can be orders of magnitude more reactive than the original bases, as demonstrated for the reaction of 8-hydroxyguanine with singlet oxygen. The ratio of the various types of m…