Detoxification enzymes

Abstracto


La desintoxicación es una necesidad y sencilla para el organismo de eliminación de sustancias no deseadas. Este efecto más de 300 millones de estadounidenses y casi 8 mil millones de personas en la Tierra hoy. Los vivos, los muertos y los no nacido. Tos, eliminación de desechos, vómitos y micción y órganos vitales que expulsan y filtrar. El cuerpo es un agente autocurativo diseñado para mantener a la persona en homeostasis. Este estudio abre up prácticas de desintoxicación tratamientos y conceptos en medicina alternativa. La desintoxicación es muy útil para pacientes y clientes que padecen enfermedades crónicas. Esto incluso puede ser una enfermedad mental. que involucran la mente, alergias estacionales, ansiedad o artritis y obesidad y factores ambientales como el cáncer. La terapia de desintoxicación se usa cuando la medicina convencional no puede diagnosticar o tratar. Enfermedad de enfoque holístico / sensibilidad química múltiple y fibromialgia. A veces el El cuerpo puede tener intolerancia a ciertos tipos de alimentos para ingerir, insomnio, dolor de garganta y pérdida o aumento de peso. Esto se basa fundamentalmente en que las enfermedades causadas por la acumulación de sustancias tóxicas Toxinas que se encuentran en el cuerpo. Entendiendo las toxinas existentes y evitándolas de nuevas toxinas es esencial para la persona del proceso de curación. Personas con el propósito de este estudio podrán comprender las partes de una salud óptima para traer bienestar a sí mismos.

The activity of human cytosolic glutathione S-transferases (GSTs) can positively or negatively be changed by various compounds. It is for instance known that RRR-alpha-tocopherol inhibits GST P1-1 [Haaften van R.I.M. et al. (2001) Alpha-tocopherol inhibits human glutathione S-transferase pi. BBRC 280, 631-633]. The effect of RRR-alpha-tocopherol on the other isoenzymes of GST in purified forms of the isoenzymes and in human liver cytosol (GST M and GST A) and lysate of human erythrocytes (GST P) is studied. It is found that all isoenzymes (purified enzymes and enzymes present in homogenates) are inhibited, in a concentration-dependent way, by RRR-alpha-tocopherol. GST P is in both cases inhibited with the highest potency compared to the other isoenzymes. It also appeared that the purified GST P1-1 isoenzyme is non-competitively inhibited by RRR-alpha-tocopherol. The IC(50) values of RRR-alpha-tocopherol for the purified isoenzymes of GST are much lower compared to the IC(50) values for human lysate and human liver cytosol. This is probably due to binding of RRR-alpha-tocopherol to proteins, e.g. albumin and hemoglobin, with higher affinity than to GST; so more RRR-alpha-tocopherol is needed to inhibit the enzyme. However, the inhibition of GSTs by RRR-alpha-tocopherol can still be of physiological relevance, because due to dermal application of cosmetic products very high concentrations vitamin E can be reached in the skin, where GST P1-1 is present. RRR-alpha-tocopherol might also be a good lead compound for the development of a new class of inhibitors of GST that can be used as adjuvant in cancer therapy.

An examination of insect resistance was determined by several steps, i.e. standard sensitivity, resistance diagnosis, and determination of resistance level. Each phase was tested with feeding and residue contact methods at glass tube. Resistance ratio (RR) was determined by comparing LC50 value of field population with standard population. Field population of C. pavonana was classified resistant if it had RR 5 4. Biochemistry analysis of resistance was conducted to population of C. pavonana showing resistance to prophenophos insecticide. The activity analysis of acetylcholine esterase (ACHE), esterase, and Glutation S transferase was done with spectrophotometer method. Insect which are resistant to prophenophos insecticide was tested for its sensitivity to Barringtonia asiatica seed extract. Result indicated that C. pavonana population from Pengalengan showed resistance to prophenophos synthetic insecticide. Using contact test, the highest resistance ratio value was 4.04, while by feeding assay the RR was 2.78. The study on biochemical resistance mechanisms of each field population of C. pavonana showed various activities of enzymatic detoxification. This could be due to the difference in the kind of insecticides exposed to each field population of C. pavonana. Since RR value from the contact test was higher than that of the feeding test, the resistance development of C. pavonana to synthetic insecticides was probably caused by physiological and biochemical changes in insect cuticle rather than the activity of detoxification enzyme. Methanolic seed extract of B. asiatica can be used as an alternative of resistance management of C. pavonana to prophenophos synthetic insecticide.

Reactive oxygen species and various electrophiles are involved in the etiology of diseases varying from cancer to cardiovascular and pulmonary disorders. The human body is protected against damaging effects of these compounds by a wide variety of systems. An important line of defense is formed by antioxidants. Vitamin E (consisting of various forms of tocopherols and tocotrienols) is an important fat-soluble, chain-breaking antioxidant. Besides working as an antioxidant, this compound possesses other functions with possible physiological relevance. The glutathione-dependent enzymes form another line of defense. Two important enzymes in this class are the free radical reductase and glutathione S-transferases (GSTs). The GSTs are a family of phase II detoxification enzymes. They can catalyze glutathione conjugation with various electrophiles. In most cases the electrophiles are detoxified by this conjugation, but in some cases the electrophiles are activated. Antioxidants do not act in isolation but form an intricate network. It is, for instance, known that vitamin E, together with glutathione (GSH) and a membrane-bound heat labile GSH-dependent factor, presumably an enzyme, can prevent damaging effects of reactive oxygen species on polyunsaturated fatty acids in biomembranes (lipid peroxidation). This manuscript reviews the interaction between the two defense systems, vitamin E and glutathione-dependent enzymes. On the simplest level, antioxidants such as vitamin E have protective effects on glutathione-dependent enzymes; however, we will see that reality is somewhat more complicated.

The glutathione S-transferase (GST) isoenzyme superfamilies detoxify a wide-range of toxic chemicals and environmental substances are extensively expressed in mammalian tissues. Liver and pancreas are the sites where cytosolic Phase I and phase II biotransformation GSTs enzymes have characteristic expression. GSTs play a key role in the deactivation of reactive oxygen species (ROS) and the metabolism of lipids, chemotherapeutic agents. GSTs are mainly involved in conjugation of reduced glutathione (GSH) with diverse substrates specificity and it is possible that genetic variations in these enzymes will influence cellular response to the environmental agents. GSTs are overexpressed in response to a chemical or oxidative stress as an adaptive physiology and upregulated in cancerous state of organ or tissue. GSTs are essentially involved in susceptibility to various forms of cancer as they are vital in detoxification mechanism to metabolize the environmental carcinogens. GSTM1 encodes for a class mu GST isoenzyme involved in polycyclic aromatic hydrocarbons (PAHs) detoxification. The substrates of GSTM1 include benzo(a)pyrene, benzo(c)phenanthrene, benzo(g)chrysene and other carcinogens. They can catalyze in-vitro GSH conjugation with several potent carcinogenic epoxides including aflatoxin B1(AFB1)8,9-epoxide and electrophilic metabolites of PAHs present in tobacco smoke. Ethylene dibromide, p-nitrobenzyl chloride, p-nitrophenetyl bromide, methyl chloride, and methyl iodide, are known substrates for GSTT1 or GST Theta (θ). GST Theta is most primitive among other known GSTs and widely expressed in nature.

We assessed whether exposure to environmentally-relevant mixtures of four organophosphorus insecticides
(OPs) exerted adverse effects on honey bees. Adult and worker bees were orally exposed for five
days under laboratory conditions to mixtures of four insecticides, diazinon, malathion, profenofos and
chlorpyrifos at two concentrations. Concentration in the mixtures tested were equivalent to the median
and 95th centile concentrations of the OPs in honey, as reported in the literature. Effects on survival,
behavior, activity of acetylcholinesterase (AChE), and expression of genes important in detoxification
of xenobiotics and immune response were examined. Survival of worker bees was not affected by exposure
to median or 95th centile concentrations of the OPs. Activity of AChE was significantly greater in
worker bees exposed to the 95th centile concentration mixture of OPs compared to the median concentration
mixture. Expression of genes involved in detoxification of xenobiotics was not affected by treatment,
but the abundance of transcripts of the antimicrobial peptide hymenoptaecin was significantly
greater in worker honey bees exposed to the median concentration mixture. Results suggest that
short-term exposure to environmentally relevant concentrations of a mixture of OPs do not adversely
affect worker honey bees.

Aims:  To study protease production from four Bacillus species.
To optimize the production of extracellular protease by testing
various environmental and nutritional factors and its application as
a contact lens cleanser.
Methodology: The assay was carried out in duplicates. Cultures of
Bacillus subtilis, Batcillus licheniformis, Bacillus thermophilus,
and  Bacillus cereus  were used for Protease production and assay.
Sterile Bushnell  –  Hass medium containing 1% casein was used.
The clear zone of casein hydrolysis indicated protease secretion.
Protease assay was done using modified sigma protocol for
enzymatic assay of protease. Effect of incubation time, pH,
temperature and aeration on protease production was studied.
Diameter of colony and zone of clearance was measured and Cx
ratio was calculated. The best protease producer was selected.
Extracted and crude protease enzymes were added to artificial tear
solution prepared with 0.2% lysozyme. Enzyme treatment was
done for 10, 30, 60 and 90 min at optimum temperatures of
respective enzymes. Light  transmission readings were recorded
using visible range spectrophotometer at 285 nm.
Results:  All four species of Bacillus produced protease enzyme.
Bacillus subtilis (Cx ratio=6) was the best protease producer. 37
o
C
temperature, 48 hrs of incubation and pH 7.5 was optimum for
maximum production of protease from Bacillus subtilis. Optimum
temperature and pH for the crude enzyme activity was 40ºC and 8.
The optimum ammonium sulfate fractionation (40% (w/v)
saturation) showed 4.76 fold increase in the specific activity of the
crude extract. Protein solution was degraded by purified enzyme in
30 min whereas crude enzyme required 60 min.
Conclusion:  Protease enzyme extracted from  Bacillus subtilis
showed good activity against artificial tear solution.

An examination of insect resistance was determined by several steps, i.e. standard sensitivity, resistance diagnosis, and determination of resistance level. Each phase was tested with feeding and residue contact methods at glass tube. Resistance ratio (RR) was determined by comparing LC50 value of field population with standard population. Field population of C. pavonana was classified resistant if it had RR 5 4. Biochemistry analysis of resistance was conducted to population of C. pavonana showing resistance to prophenophos insecticide. The activity analysis of acetylcholine esterase (ACHE), esterase, and Glutation Stransferase was done with spectrophotometer method. Insect which are resistant to prophenophos insecticide was tested for its sensitivity to Barringtonia asiatica seed extract. Result indicated that C. pavonana population from Pengalengan showed resistance to prophenophos synthetic insecticide. Using contact test, the highest resistance ratio value was 4.04, while by fe...

The insecticide resistance status of Culex quinquefasciatus Say (Diptera: Culicidae) to DDT and deltamethrin across army cantonments and neighbouring villages in northeastern India was investigated. In India, DDT is still the insecticide of choice for public health programmes. In military stations, pyrethroids, especially deltamethrins, are used for insecticide-treated nets (ITNs). Recent information on the levels of resistance to DDT and deltamethrin in mosquito populations of northeastern India is scare. Continued monitoring of insecticide resistance status, identification of the underlying mechanisms of resistance in local mosquito populations and the establishment of a baseline data bank of this information are of prime importance. Insecticide susceptibility assays were performed on wild-caught adult female Cx. quinquefasciatus mosquitoes to the discriminating doses recommended by the World Health Organisation (WHO) to DDT (4%) and deltamethrin (0.05%). Across all study sites, mortality as a result of DDT varied from 11.9 to 50.0%, as compared with 91.2% in the susceptible laboratory strain (S-Lab), indicating that Cx. quinquefasciatus is resistant to DDT. The species was found to be 100% susceptible to deltamethrin in all study sites except Benganajuli and Rikamari. Knockdown times (KDT) in response to deltamethrin varied significantly between study sites (P < 0.01) from 8.3 to 17.8 min for KDT 50 and 37.4 to 69.5 min for KDT 90. All populations exceeded the threshold level of alpha-esterase, beta-esterase and glutathion S-transferase (GST) established for the SLab susceptible strain, and all populations had 100% elevated esterase and GST activity, except Missamari and Solmara. Beta-esterase activity in Field Unit II (96.9%) was less than in any of the other populations. Benganajuli had the highest activity level for all the enzymes tested. There was a significant correlation between all enzyme activity levels and insecticide resistance phenotype by populations (P < 0.05). The results presented here provide the first report and baseline information of the insecticide resistance status of Cx. quinquefasciatus in northeastern India, and associated information about biochemical mechanisms that are essential for monitoring the development of insecticide resistance in the area.

Glutathione transferases (GSTs) are dimeric enzymes containing one active-site per monomer. The omega-class GSTs (hGSTO1-1 and hGSTO2-2 in humans) are homodimeric and carry out a range of reactions including the glutathionedependant reduction of a range of compounds and the reduction of S-(phenacyl)glutathiones to acetophenones. Both types of reaction result in the formation of a mixed-disulfide of the enzyme with glutathione through the catalytic cysteine (C32). Recycling of the enzyme utilizes a second glutathione molecule and results in oxidized glutathione (GSSG) release. The crystal structure of an active-site mutant (C32A) of the hGSTO1-1 isozyme in complex with GSSG provides a snapshot of the enzyme in the process of regeneration. GSSG occupies both the G (GSH-binding) and H (hydrophobic-binding) sites and causes rearrangement of some H-site residues. In the same structure we demonstrate the existence of a novel ''ligandin'' binding site deep within in the dimer interface of this enzyme, containing S-(4nitrophenacyl)glutathione, an isozyme-specific substrate for hGSTO1-1. The ligandin site, conserved in Omega class GSTs from a range of species, is hydrophobic in nature and may represent the binding location for tocopherol esters that are uncompetitive hGSTO1-1 inhibitors.

Glutathione S-transferase is a phase II detoxification enzyme that can be inactivated by hydrogen peroxide (H2O2). During oxidative stress various other reactive oxygen species are generated that are more reactive than the relatively stable H2O2. Hypochlorous acid (HOCl) is a powerful oxidant which is highly reactive towards a range of biological substrates. We studied the influence of HOCl on the activity of GST P1-1. HOCl inhibits purified glutathione S-transferase P1-1 in a concentration dependent manner with an IC50-value of 0.6 microM, which is more than 1000 times as low as IC50 reported for H2O2. HOCl lowered the Vmax value, but did not affect the Michaelis Menten constant (Km) for CDNB. Our results show that HOCl is a potent, non-competitive inhibitor of GST P1-1. The relevance of this effect is discussed.

In recent decades, our knowledge of the genetics and functional genomics of drug-metabolizing enzymes has increased and a wealth of data on drug-related ‘omics’ has become available. Despite the availability of large amounts of biological information on xenobiotic biotransformation, the number of available biotransformation pathway maps that can easily be used for visualization of multiple omics data is limited. Here, we created integrated biotransformation pathway maps suitable for multiple omics analysis using PathVisio. The ease of visualizing data on these maps was demonstrated by using published microarray data from human hepatocyte-like cell models, exemplifying – where a sufficient capacity for metabolizing chemicals is a prerequisite for a suited model – how the biotransformation pathway maps can be used for model selection.

The insecticide resistance status of Culex quinquefasciatus Say (Diptera: Culicidae) to DDT and deltamethrin across army cantonments and neighbouring villages in northeastern India was investigated. In India, DDT is still the insecticide of choice for public health programmes. In military stations, pyrethroids, especially deltamethrins, are used for insecticide-treated nets (ITNs). Recent information on the levels of resistance to DDT and deltamethrin in mosquito populations of northeastern India is scare. Continued monitoring of insecticide resistance status, identification of the underlying mechanisms of resistance in local mosquito populations and the establishment of a baseline data bank of this information are of prime importance. Insecticide susceptibility assays were performed on wild-caught adult female Cx. quinquefasciatus mosquitoes to the discriminating doses recommended by the World Health Organisation (WHO) to DDT (4%) and deltamethrin (0.05%). Across all study sites, mortality as a result of DDT varied from 11.9 to 50.0%, as compared with 91.2% in the susceptible laboratory strain (S-Lab), indicating that Cx. quinquefasciatus is resistant to DDT. The species was found to be 100% susceptible to deltamethrin in all study sites except Benganajuli and Rikamari. Knock-down times (KDT) in response to deltamethrin varied significantly between study sites (P < 0.01) from 8.3 to 17.8 min for KDT50 and 37.4 to 69.5 min for KDT90. All populations exceeded the threshold level of alpha-esterase, beta-esterase and glutathion S-transferase (GST) established for the S-Lab susceptible strain, and all populations had 100% elevated esterase and GST activity, except Missamari and Solmara. Beta-esterase activity in Field Unit II (96.9%) was less than in any of the other populations. Benganajuli had the highest activity level for all the enzymes tested. There was a significant correlation between all enzyme activity levels and insecticide resistance phenotype by populations (P < 0.05). The results presented here provide the first report and baseline information of the insecticide resistance status of Cx. quinquefasciatus in northeastern India, and associated information about biochemical mechanisms that are essential for monitoring the development of insecticide resistance in the area.

In various cosmetic and dietary products α-tocopherol is added as a tocopherol ester. Therefore we have studied the effect of various tocopherol derivatives on GST P1-1 activity. It was found that GST P1-1 is inhibited, in a concentration dependent manner, by these compounds. Of the compounds tested, the tocopherols were the most potent inhibitors of GST P1-1; the concentration giving 50% inhibition (IC50) is <1 μM. The esterified tocopherols and α-tocopherol quinone also inhibit the GST P1-1 activity at a very low concentration: for most compounds the IC50 was below 10 μM. RRR-α-Tocopherol acetate lowered the Vmax values, but did not affect the Km for either 1-chloro-2,4-dinitrobenzene or GSH. This indicates that the GST P1-1 enzyme is non-competitively inhibited by RRR-α-tocopherol acetate. The potential implications of GST P1-1 inhibition by tocopherol and α-tocopherol derivatives are discussed.

α-Tocopherol is the most important fat-soluble, chain-breaking antioxidant. It is known that interplay between different protective mechanisms occurs. GSTs can catalyze glutathione conjugation with various electrophiles, many of which are toxic. We studied the influence of α-tocopherol on the activity of the cytosolic π isoform of GST. α-Tocopherol inhibits glutathione S-transferase π in a concentration-dependent manner, with an IC50-value of 0.5 μM. At α-tocopherol additions above 3 μM there was no GST π activity left. α-Tocopherol lowered the Vmax values, but did not affect the Km for either CDNB or GSH. This indicates that the GST π enzyme is noncompetitively inhibited by α-tocopherol. An inhibition of GST π by α-tocopherol may have far-reaching implications for the application of vitamin E.