Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.3.5.1 (succinate dehydrogenase)
 8,177 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pigment-binding protein of the facultatively phototrophic bacterium Rhodospeudomonas capsulata could be selectively synthesized in toluene-treated cells as well as in homologous and heterologous cell-free translation systems by isolated polysomes. It is shown that the pigment-binding polypeptides of the light-harvesting complexes are encoded by messenger RNA of extreme longevity. The dependence of their synthesis on the concomitant synthesis of tetrapyrroles was demonstrated in the toluene-treated cells. The large Mr-28 000 polypeptide of the reaction center and the Mr-10 000 pigment-binding polypeptide of the light-harvesting complex II were found to be synthesized by free (water-soluble) polysomes without a cleavable 'leader' or 'signal' peptide [reviewed by W. Wickner (1979) Annu. Rev. Biochem. 48, 23-45]. The Mr-10 000 polypeptide, as synthesized in vitro, was studied in more detail. Unlike the membrane-assembled polypeptide in vivo it was insoluble in an organic solvent mixture (chloroform/methanol 1:1, v/v). After detergent denaturation in the presence of membrane isolated from the organism it became organic-solvent-soluble. Obviously the polypeptide could be induced to assume alternative conformations in which its apolar residues were either exposed to the solvent or buried within. These findings, in agreement with Wickner's hypothesis, indicate that the Mr-10 000 polypeptide may enter the lipid bilayer by a 'membrane-triggered' conformational change.
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PMID:Synthesis of pigment-binding protein in toluene-treated Rhodopseudomonas capsulata and in cell-free systems. 636 74

Groups of CFY rats were exposed to toluene inhalation as follows: both males and females to 1000 mg/m3 6 h daily five times a week for 6 months; only males to 3500 mg/h3 8 h daily every day for 6 months; and only males to 1500, 3000 and 6000 mg/m3 8 h daily for 4 weeks. Control groups were exposed to air inhalation under identical conditions. Toluene was found to inhibit growth but to cause no abnormal light-microscopical changes. Hepatic changes were: (i) Signs of compensation such as increased relative liver weight, SER proliferation; increased succinate dehydrogenase activity; a decrease in glycogen content; increased cytochrome P-450 and b5 concentration; increased hepatic aniline hydroxylase and aminopyrine N-demethylase activity. (ii) Non-specific subcellular effect was observed in a small number of hepatocytes, namely RER dilatation, separation of ribosomes, mitochondria of variable shapes, an increased number of autophagous bodies. As regards indicators of the hepatic function, BSP retention decreased, GOT and GPT activity did not change. The changes were observed in both sexes, were dose-dependent and reversible, and showed no--or only a slight--dependence on exposure time. Chronic toluene exposure has no specific hepatotoxic effect leading to chronic liver disease.
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PMID:Effect of toluene inhalation on the liver of rats--dependence on sex dose and exposure time. 744 Sep 61

Toluene appears to have adverse effects on the human auditory system, but it is difficult to estimate its potency since it is commonly present in the workplace in combination with noise exposure; workplace noise exposures are often highly variable. Studies designed to assess toluene ototoxicity specifically have been limited to high-dose studies in a single laboratory animal model, the rat. Here permanent hearing loss has been observed at concentrations of 1000 ppm toluene and greater after inhalation exposure for 5 days, 6 h/day. The OSHA threshold limit value for toluene is only 100 ppm. The current study focuses on the onset of toluene ototoxicity acutely in the guinea pig and in adducing a mechanism of effect. In this study, evidence is presented for the impairment of auditory function by toluene in the guinea pig, at a concentration substantially lower than that used for studying permanent impairment in the rat. The impaired function was correlated with reduced energy metabolism in outer hair cells. Assessment of auditory function was made using distortion product otoacoustic emissions (DPOAE) with subsequent measurement of succinate dehydrogenase (SDH) staining density in hair cells using surface preparations. Temporary disruption of auditory function in guinea pigs is seen in subjects exposed to 250, 500, and 1000 ppm toluene for 8 h/day, 5 day/week for 1 and 4 weeks. Concentrations as low as 250 ppm toluene were able to disrupt auditory function acutely in the guinea pig, and 500 and 1000 ppm toluene produced greater acute dysfunction. SDH staining suggests that reduced enzyme activity in the midfrequency region of the cochlea occurs acutely following toluene exposure. Although the auditory dysfunction progressed between 1 and 4 weeks of exposure, a permanent loss did not develop for these subjects and hair cell death was not seen. The current study identifies early evidence of auditory system impairment in the guinea pig at low toluene concentration and evidence for impairment of energy production in hair cells. While even a transient auditory impairment has implications for workplace safety, additional study on the transition from such acute effects to permanent impairment is essential.
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PMID:Low-level toluene disrupts auditory function in guinea pigs. 1093 75