Search results for "Mixed Function Oxygenase"
showing 10 items of 49 documents
Thyroid hormone controls carnitine status through modifications of gamma-butyrobetaine hydroxylase activity and gene expression.
2002
The carnitine system plays a key role in beta-oxidation of long-chain fatty acids by permitting their transport into the mitochondrial matrix. The effects of hypothyroidism and hyperthyroidism were studied on gamma-butyrobetaine hydroxylase (BBH), the enzyme responsible for carnitine biosynthesis in the rat. In rat liver, BBH activity was decreased in the hypothyroid state and increased in hyperthyroid animals. The modifications in BBH activity correlated with changes in the enzyme Vmax values. These changes were shown to be related to hepatic BBH mRNA abundance. Thyroid hormones are known to interact with lipid metabolism, in particular by increasing long-chain fatty acid oxidation through…
Difference between Guinea Pig and Rat in the Liver Peroxisomal Response to Equivalent Plasmatic Level of Ciprofibrate
1996
Abstract Guinea pig was previously classified as a species nonresponsive to peroxisome proliferators. However, none of the previous reports was based on pharmacokinetic data. Here, after a comparative pharmacokinetic study between guinea pig and rat, we evaluate the guinea pig liver peroxisomal response to ciprofibrate, a hypolipemic agent and a potent peroxisome proliferator in rat. (1) Pharmacokinetic results show that plasmatic concentrations of ciprofibrate are equivalent in guinea pig and rat when guinea pigs are treated with ciprofibrate at 30 mg/kg twice a day and rats are treated at 3 mg/kg once a day. (2) The treatment of guinea pigs at 30 mg/kg twice a day for 2 weeks leads to a s…
Role of thyroid state on induction by ciprofibrate of laurate hydroxylase and peroxisomal enzymes in rat liver microsomes.
1993
The effects of hypothyroidism and hyperthyroidism upon liver microsomal omega-laurate hydroxylase activity (cytochrome P450 IV A1-dependent), peroxisome proliferation marker enzyme activities and acyl CoA oxidase (AOX) expression induced by ciprofibrate (2 mg/kg/day during 8 days) were studied in the male Wistar rat so as to clarify firstly the possible involvement of thyroid hormones in the modification of peroxisomal ciprofibrate-induced enzyme activities in relation to hepatic microsomal cytochrome P450 IV A1 induction, and secondly the possible direct effect of thyroid hormones on the gene expression of specific peroxisomal enzymes. No significant change was found in the ciprofibrate-in…
Enhancement of activities relative to fatty acid oxidation in the liver of rats depleted of l-carnitine by d-carnitine and a γ-butyrobetaine hydroxyl…
1995
Abstract This study was designed to examine whether the depletion of l -carnitine may induce compensatory mechanisms allowing higher fatty acid oxidative activities in liver, particularly with regard to mitochondrial carnitine palmitoyltransferase I activity and peroxisomal fatty acid oxidation. Wistar rats received d -carnitine for 2 days and 3-(2,2,2-trimethylhydrazinium)propionate (mildronate), a non-competitive inhibitor of γ-butyrobetaine hydroxylase, for 10 days. They were starved for 20 hr before being sacrificed. A dramatic reduction in carnitine concentration was observed in heart, skeletal muscles and kidneys, and to a lesser extent, in liver. Triacylglycerol content was found to …
Isolation and Characterization of Novosphingobium sp. Strain MT1, a Dominant Polychlorophenol-Degrading Strain in a Groundwater Bioremediation System
2002
ABSTRACT A high-rate fluidized-bed bioreactor has been treating polychlorophenol-contaminated groundwater in southern Finland at 5 to 8°C for over 6 years. We examined the microbial diversity of the bioreactor using three 16S ribosomal DNA (rDNA)-based methods: denaturing gradient gel electrophoresis, length heterogeneity-PCR analysis, and restriction fragment length polymorphism analysis. The molecular study revealed that the process was dependent on a stable bacterial community with low species diversity. The dominant organism, Novosphingobium sp. strain MT1, was isolated and characterized. Novosphingobium sp. strain MT1 degraded the main contaminants of the groundwater, 2,4,6-trichloroph…
Evidence for Natural Horizontal Transfer of the pcpB Gene in the Evolution of Polychlorophenol-Degrading Sphingomonads
2002
ABSTRACT The chlorophenol degradation pathway in Sphingobium chlorophenolicum is initiated by the pcpB gene product, pentachlorophenol-4-monooxygenase. The distribution of the gene was studied in a phylogenetically diverse group of polychlorophenol-degrading bacteria isolated from contaminated groundwater in Kärkölä, Finland. All the sphingomonads isolated were shown to share pcpB gene homologs with 98.9 to 100% sequence identity. The gene product was expressed when the strains were induced by 2,3,4,6-tetrachlorophenol. A comparative analysis of the 16S rDNA and pcpB gene trees suggested that a recent horizontal transfer of the pcpB gene was involved in the evolution of the catabolic pat…
Questioning the role of salicylic acid and cytosolic acidification in mitogen-activated protein kinase activation induced by cryptogein in tobacco ce…
2001
Elicitors of plant defence reactions, oligogalacturonides and cryptogein, an elicitin produced by Phytophthora cryptogea, were previously shown to induce a rapid and transient activation of two mitogen-activated protein kinases (MAPKs) in cells of tobacco [ Nicotiana tabacum L. cv. Xanthi; A. Lebrun-Garcia et al. (1998) Plant J 15:773-781]. We verified that these two MAPKs correspond to the salicylic acid-induced protein kinase (SIPK) and the wound-induced protein kinase (WIPK). The involvement of salicylic acid (SA) in cryptogein-induced MAPK activation was investigated using transgenic NahG tobacco cells expressing the salicylate hydroxylase gene and thus unable to accumulate SA. The larg…
Expression and inducibility of drug-metabolizing enzymes in preneoplastic and neoplastic lesions of rat liver during nitrosamine-induced hepatocarcin…
1987
The expression, inducibility, and regulation of four different cytochrome (cyt.) P-450 isoenzymes (PB1, PB2, MC1, and MC2) NADPH-cytochrome P-450 reductase, the glutathione transferases (GSTs) B and C and microsomal epoxide hydrolase (mEHb) have been studied during nitrosamine-induced hepatocarcinogenesis using immunohistochemical techniques. The investigations revealed basic differences in the expression of the individual drug metabolizing enzymes in the course of neoplastic development. While the two GSTs and mEHb were increased in all preneoplastic and benign neoplastic lesions, the levels of the distinct cyt. P-450 isoenzymes were characteristically different from each other. Following …
Significance of Various Enzymes in the Control of Mutagenic and Carcinogenic Metabolites Derived from Aromatic Structures
1984
One important early contribution to the control of chemical carcinogenesis is provided by the enzyme pattern responsible for the generation and disposition of reactive metabolites. Especially well studied is the important group of enzymes responsible for the control of reactive epoxides. Many natural as well as man-made foreign compounds, including Pharmaceuticals, possess olefinic or aromatic double bonds. Such compounds can be transformed to epoxides by microsomal monooxygenases present in very many mammalian organs. By virtue of their electrophilic reactivity such epoxides may spontaneously react with nucleophilic centers in the cell and thus covalently bind to DNA, RNA, and protein. Su…
NADH dehydrogenase deficiency results in low respiration rate and improved aerobic growth of Zymomonas mobilis.
2008
The respiratory chain of the ethanol-producing bacterium Zymomonas mobilis is able to oxidize both species of nicotinamide cofactors, NADH and NADPH. A mutant strain with a chloramphenicol-resistance determinant inserted in ndh (encoding an NADH : CoQ oxidoreductase of type II) lacked the membrane NADH and NADPH oxidase activities, while its respiratory d-lactate oxidase activity was increased. Cells of the mutant strain showed a very low respiration rate with glucose and no respiration with ethanol. The aerobic growth rate of the mutant was elevated; exponential growth persisted longer, resulting in higher biomass densities. For the parent strain a similar effect of aerobic growth stimulat…