Comparison of highly purified sheep liver and lung nadph-cytochrome P-450 reductases by the analysis of kinetic and catalytic properties

1. Reductase was purified to electrophoretic homogeneity from sheep liver and lung microsomes. The specific activity of both enzymes ranged from 55 to 66 μ mol cytochrome c reduced/min/mg protein. 2. Liver and lung reductases appeared to have similar kinetic and spectral properties. Km, (NADPH) and Km (cytochrome c) values were calculated to be 14.3 ± 1.23μM and 22.2 ± 2.78 μM for liver and 11.1 ±0.70 μM and 20.0 ± 2.15μM for lung reductase, respectively. Kinetic studies showed that cytoehrome c can bind the oxidized form of the enzyme as well as its reduced form and both reductases operated through a ping-pong type mechanism. 3. These reductases cannot be distinguished on the basis of monomer molecular weights (Mr 78,000) except that the liver reductase was found to be more susceptible to proteolytic attack. 4. Both reductases supported aniline 4-hydroxylation and ethylmorphine N-demethylation reactions to the same extent in the reconstituted systems. However, sheep lung reductase appeared only 36.5 and 14.8% as effective in catalyzing benzo[a]pyrene reaction as an equivalent amount of reductase from liver in the presence of liver cytochrome P-450 and 3MC-treated rat liver cytochrome P-448, respectively.Publisher's Versio

Effects of 2-arylbenzimidazoles on rat hepatic microsomal monooxygenase system

1. The effects of eight newly synthesized 2-aryl substituted benzimidazole derivatives on control and phenobarbital (PB) treated rat liver microsomal aniline 4-hydroxylase and ethylmorphine N-demethylase activities, and their binding to control and PB-treated rat liver microsomal oxidized cytochrome P-450 are presented. 2. All compounds inhibited ethylmorphine N-demethylase activity with I50 values ranging from 8.50 × 10−4 M to 27.83 × 10−4 M in control and ranging from 2.80 × 10−4 M to 15.79 × 10−4 M in PB-treated rats. 3. Aniline 4-hydroxylase activity was inhibited by all of the compounds tested having I50 values in the range of 7.04 × 10−4 M-31.37 × 10−4 M in PB-treated rats, but only five of the compounds showed inhibitory activity in control rats. 4. Only a few significant regression coefficients could be found between the parameters of the chemicals studied and their inhibitory patterns. 5. No correlation has been observed between the binding of the derivatives and their inhibitory pattern.Publisher's Versio

N-Asetiltransferaz ve glutatyon S-transferaz teta polimorfizminin meme kanserri ile olan ilişkilerinin araştırılması

Biyolojik asetilasyon ve S-konjugasyon reaksiyonları, insan ve hayvan türlerinin ana konjugasyon reaksiyonlarından en önemli iki tanesidir. Bu çalışmada, insan meme dokusuna özel asetil koenzim A'ya bağımlı arilamin N-asetiltransferaz (E.C.2.3.1.5) ve glutatyon-S-transferaz (E.C.2.5.1.18) enzim aktiviteleri çalışılmış ve dokulardaki asetilasyon ile glutatyon transferi arasındaki ilişki incelenmiştir. Bu amaçla, meme kanserli 22 kadın hastada, N-asetiltransferaz (NAT1 ve NAT2) ve glutatyon-S-transferaz-teta-2-2 (GSTT2-2) enzim aktiviteleri, kanserli ve normal dokularda tayin edilmiştir. Normal ve kanserli dokularda ortalama değerler, sırasıyla NAT1 için 0,014$\pm$0,01 ve 0,019±0,01 nmol/dak/mg protein; NAT2 için 0,010$\pm$0,01 ve 0,034$\pm$0,03 nmol/dak/mg protein; GSTT2-2 için 0,272$\pm$0,29 ve 0,424$\pm$0,37 nmol/dak/mg protein olarak bulunmuştur.İstatistiksel analizler sonucunda , GSTT2-2 ortalama aktivitesinin kanserli dokularda kontrollere göre daha yüksek olduğu belirlenmiş; kanserli dokularda NAT1 ve GSTT2-2 aktiviteleri arasında negatif bir korelasyon olduğu gözlenmiştir. NAT1'e oranla NAT2 aktivitelerinin meme tümörlerinde belirgin bir şekilde arttığı ve GSTT2-2 aktiviteleri ile pozitif bir korelasyon sergilediği gözlemlenmiştir. Daha önceki çalışmamızda olduğu gibi, kanserli dokularda, kontrol dokularından elde edilen daha yüksek NAT2 ortalama aktivitesi olduğu ve bunun istatiksel olarak anlamlı olduğu tespit edilmiştir

Alkylphenol concentrations in two rivers of Turkey

Alkylphenol polyethoxylates (APEs) called environmental endocrine disruptors has been shown to accumulate in water around the world. In this study.. the pollution level of alkylphenolic compounds was measured and quantified in water, sediment, and the tissues of fishes collected in two rivers, Sakarya and Degirmendere Rivers, Turkey. Butylphenol (BP) were detected in sediment samples at one sampling stations of both rivers with 1.68 and 3.15 mug/g sediment, while nonylphenol (NP) were detected with the amount of 4.46 mug/g sediment in one sampling station in Degirmendere river. Fish samples also showed the presence of alkylphenolic compounds in both rivers. The level of alkylphenol pollution in two rivers of Turkey was determined to be in the range of alkylphenol level reported in Europe but lower than that of in the USA