Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0009443 (cold)
 92,137 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The hydroxymethylglutaryl-coenzyme A reductase (mevalonate:NADP+ oxidoreductase, EC 1.1.1.34) system in Fusarium oxysporum, a soil inhabiting plant pathogen, has been examined. Two forms of the enzyme catalyzing the conversion of hydroxymethylglutaryl-coenzyme A were obtained in the supernatant after precipitation at 75% (NH4)2SO4 saturation of the soluble culture extract which was previously separated from cell wall, mitochondria and microsomes. The two forms of the enzyme were separated electrophoretically. A third form, contained in the precipitate obtained at 35--75% (NH4)2SO4 saturation of the same extract, was further purified by Sephadex G-50 column chromatography. This purified form moved as a single band in sodium dodecyl sulphate electrophoresis and in immunological tests and has a molecular weight of 11 000. The apparent Michaelis constant for the substrate hydroxymethylglutaryl-coenzyme A is 21 micron at 2 micron NADP. NADPH is a more efficient reductant on a molar basis than NADH for the deacylation of the hydroxymethylglutaryl-coenzyme A substrate. Optimum activity of the enzyme was obtained at pH 7.4 and 37 degrees C. The enzyme demonstrated no cold sensitivity but rather was more stable at 4 degrees C than at 25 degrees C. The protection with dithiothreitol, though minimal compared to other systems, was more effective at the higher temperature.
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PMID:Hydroxymethylglutaryl-coenzyme A reductase. Purification and properties of the enzyme from Fusarium oxysporum. 2 7

The catalytic properties of microsomal 3-hydroxy-3-methylglutaryl coenzyme A reductase from avian liver have been investigated. Solubilized and highly purified reductase preparations were not cold labile, and enzymic activity remained unchanged following preincubation at 37 degrees C. The pH optimum was 6.8--7.0 and maximal catalytic activity was achieved with 2 mM dithiothreitol and 0.75 M KCl. The heat stability of the enzyme was studied and the addition of 0.75 M KCl, 0.8 mg/ml bovine serum albumin and 5 mM NADPH reduced the inactivation of the purified reductase associated with heat treatment at 65 degrees C. At 37 degrees C, 0.8 mg/ml bovine serum albumin enhanced the purified reductase activity by 100 (+/- 20)%. An improved assay was developed for the avian hydroxymethylglutaryl-CoA reductase and the specific activity of the purified enzyme increased from 1550 to 3300 nmol . min-1 . mg-1. The Km values of solubilized and purified reductase for D-hydroxymethylglutaryl-CoA were 1.05 micrometer and 1.62 micrometer, and for NADPH, 1 mM and 263 micrometer, respectively. The activities of the reductase preparations were non-competitively inhibited by coenzyme A, acyl-CoA esters, and hydroxymethylglutarate. MgATP also reduced avian reductase activity. These modulators may play a role in the cellular regulation of the reductase activity.
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PMID:3-Hydroxy-3-methylglutaryl coenzyme A reductase from avian liver. Catalytic properties. 3 16

The first case of fructose-1,6-diphosphatase (FDPase) deficiency in Japan showed a decreased activity of glucose-6-phosphate dehydrogenase (G6PD) in the liver, white, and red blood cells. In the enzymatic study of G6PD which was partially purified from red cells, the following characteristics were observed in the enzyme of the patient. 1) The G6PD activity of the patient was reduced to 17% of normal, but no evidence of a hemolytic episode was found in his past and family history. 2) In the investigation of G6PD of the patient, no abnormalities were observed in its enzymatic parameters such as electrophoretic mobility, Km for G6P and NADP, Ki for NADPH, the utilization of 2-deoxy G6P and deamino NADP, heat-stability, and pH curves. 3) The dissociation constants of red blood cell G6PD for NADP and NADPH, which were obtained from the investigations on the reactivation of cold-inactivated G6PD at 37 degrees C, were about 3 times higher in the patient as compared to the values of the normal controls. Based on these findings, it might be concluded that the G6PD deficiency found in the red blood cells of this case of a FDPase deficiency is a unique variant, which could not be characterized by using only the method recommended by a World Health Organization (WHO) scientific group. Considering that the abnormality observed in the G6PD of this patient was a decrease in the affinity of the enzyme for its coenzymes, the dissociation constants for the coenzymes in reactivation process might be another important kinetic parameter in characterizing the G6PD deficiency.
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PMID:Deficiency of glucose-6-phosphate dehydrogenase found in a case of hepatic fructose-1,6-diphosphatase deficiency. 23 Apr 49

The ability of human abdominal, breast and axillary fat to convert androgens into estrogens was investigated by incubating labeled substrates in the presence of NADPH with a variety of cell preparations. The incubation products were subjected to phenolic partition, paper chromatography, methyl-ether formation, repeat chromatography and crystallization with cold carrier reference standards to constant specific activity. Androstenedione was converted to estrone and, to a lesser extent, to 17beta-estradiol by crude homogenates, minces, fat-free particulate fractions (1,000-100,000 time g) and isolated fat cells obtained from abdominal, breast or axillary fat. Testosterone was found to be aromatized as actively as androstenedione, but inthis case more 17 beta-estrodiol was formed than estrone. 19-Hydroxyandrostenedione-2 also served as substrate, givingresults similar to those obtained with androstenedione. Fat tissue obtained from cancerous breasts was found to be as active as normal breast fat (1-4 pg/g fat/90 min) and within the range found for abdominal fat (1-27 pg/g fat/90 min). In each case in which axillary fat was compared to breast fat from the same subject, the activity of the axillary fat was 5 to 10 times higher. The results indicate a possible role of adipose tissue as a significant extra-gonadal source of estrogens.
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PMID:Aromatization of androgens by human abdominal and breast fat tissue. 23 75

Solubilized 3-hydroxy-3-methylglutaryl coenzyme A reductase (EC 1.1.1.34) from rat liver microsomes has been reported to be reversibly inactivated by temperatures below 19 degrees C. Cold inactivation has now been found to be completely prevented by NADPH and by NADP+ at a concentration of 3 mM. NADPH, however, was more active than NADP+ at lower concentrations and prevented 50% of the cold inactivation at 0.2 mM, whereas a 1.1 mM NADPH+ without effect and the substrate 3-hydroxy-3-methylglutaryl coenzyme A prevented only 30% of the cold inactivation at a concentration 50 times greater than the Km value.
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PMID:Prevention of cold inactivation of 3-hydroxy-3-methyl-glutaryl coenzyme A reductase by NADPH. 23 46

The ultrastructural localization of glucose-6-phosphate dehydrogenase (NADP-linked) has been attempted in steroid-secreting cells. Rat adrenocortical cells and newt testicular glandular cells were fixed in an ice-cold mixture of 1% methanol-free formaldehyde and 0.25% glutaraldehyde. Potassium ferricyanide was used as the final electron acceptor. After incubation, the final copper ferrocyanide precipitate is exclusively observed in the hyaloplasm of these cells, provided that an electron carrier (1.0 mM PMS) has been added to the medium in order to by-pass the tissue "diaphorase" (NADPH-ferricyanide reductase) reaction. No precipitate appears in the absence of glucose-6-phosphate (substrate). Incubation in a medium devoid of PMS results in an exclusively mitochondrial reaction; the latter is that of the "diaphorase", which in these cells is mitochondrial. These results prove the importance of utilizing exogenous electron carriers (such as PMS) in coenzyme-linked dehydrogenase cytochemistry. Although polyvinyl alcohol was included in the washing and incubation media, in order to increase their viscosity, problems still exist concerning ultracytochemical localization of this "soluble" enzyme; these problems are discussed in the paper.
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PMID:Ultrastructural demonstration of glucose-6-phosphate dehydrogenase activity in steroid-secreting cells. 50 Apr 6

The present study was undertaken to determine covalent binding of [1,2-14C]ethylene dibromide (EDB) to albumin under in vivo and in vitro conditions. For the in vivo covalent binding, 25 mg/kg body weight of [1,2-14C]EDB was given daily to male rats for 12 consecutive days and the animals were sacrificed at 24 h following the last dose. Blood was withdrawn from inferior vena cava in heparinized tubes and plasma was separated, dialyzed against ice-cold 10 mM phosphate buffer (pH 7.4) and then subjected to size-exclusion high-performance liquid chromatography (SE-HPLC). A major radioactive peak eluted at an elution volume corresponding to 65,000 dalton molecular mass was found to be associated to albumin at a level of 0.14 nmol equivalent EDB/mg protein. For the in vitro covalent binding, human plasma or purified albumin was incubated with [1,2-14C]EDB in the presence of phenobarbital-treated rat liver microsomes and NADPH-generating system for 2 h at 37 degrees C. The 100,000 x g supernatant of the incubation mixture was dialyzed extensively and analyzed as described for the in vivo studies. Approximately 0.28 nmol equivalent EDB/mg protein was found to be associated to albumin (about 2-fold higher than the in vivo binding). Binding of 14C-label to albumin under in vivo and in vitro conditions was further supported by the affinity chromatography of albumin fraction isolated by SE-HPLC. Reversed-phase HPLC analysis of pronase digest of the albumin obtained from in vitro studies indicated formation of several amino acid adducts of EDB and/or its metabolites. Structure elucidation of such amino acid adducts will be helpful in developing a relatively non-invasive method of measuring the EDB exposure.
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PMID:Covalent binding of ethylene dibromide and its metabolites to albumin. 141 7

Constitutional lipid peroxidation in randomly selected 32 cases of clinically advanced carcinoma from human gastrointestinal tract (20 cases), breast (8 cases) and kidney (4 cases) was examined histochemically in frozen sections using cold Schiff's reagent. Only two cases of gastrointestinal carcinoma were positive by the reagent. Non-cancerous parenchymal cells were negative. These findings suggest that detectable constitutional lipid peroxidation seldom occurs in either cancerous or normal tissues. The capacity for normal and neoplastic tissues to undergo lipid peroxidation was also studied by incubation with an iron-NADPH pro-oxidant system. Normal parenchymal cells showed, to various degrees, a positive reactivity. In gastrointestinal carcinoma, 6 out of 7 cases of well differentiated adenocarcinoma reacted positively, whereas 2 out of 8 cases of moderately to poorly differentiated adenocarcinoma disclosed weakly positive reactions. Mucinous adenocarcinomas (4 cases) were all negative. Signet-ring cell carcinoma (1 case) was positive. One out of 8 cases of breast cancer also showed positive reaction. Four renal cell carcinomas were all negative. Cancer cells have lower capacity to undergo lipid peroxidation than normal cells, when the iron-NADPH pro-oxidant system was employed. In gastrointestinal carcinoma, the ability to undergo lipid peroxidation by the iron-NADPH pro-oxidant seems to be correlated with their histological differentiation. This fact may suggest that differences in lipid composition or the NADPH enzyme system exist between well differentiated and poorly differentiated gastrointestinal malignancies.
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PMID:Histochemical detection of lipid peroxidation in human gastrointestinal, mammary and renal carcinomas. 144 47

Previous studies showed that hydrocarbon induction of hepatic microsomal monooxygenase activity is attenuated in the teleost fish Fundulus heteroclitus acclimated to low temperature. The basis of that attenuation, and the effects of temperature on monooxygenase activity, were examined by analyzing liver cytochrome P4501A (CYP1A) mRNA, protein, and catalytic activity in control and beta-naphthoflavone (BNF)-treated F. heteroclitus acclimated to 6 or 16 degrees C. There were no temperature-related differences in total P450 content, NADPH-cytochrome c (P450) reductase activity, ethoxyresorufin O-deethylase (EROD) activity, or immunoquantified CYP1A content in hepatic microsomes of untreated fish. Fish acclimated to 16 degrees C and given a single intraperitoneal injection of BNF exhibited a rapid rise and fall in CYP1A mRNA content and an induction of EROD activity and CYP1A protein that was undiminished over 7 days. Similarly treated fish acclimated at 6 degrees C showed an increase in CYP1A mRNA content greater than that in 16 degrees C fish, but with no significant increase in EROD activity or CYP1A content over 7 days. Examined over a longer term, microsomal EROD activity was significantly induced by BNF in fish at both temperatures; activity peaked at 5-7 days in 16 degrees C fish, while in 6 degrees C fish the activity continued to rise slowly over 25 days. However, the greatest activity reached in 6 degrees C fish (0.68 nmol/min/mg) was less than half that seen in the warmer animals (1.46 nmol/min/mg). Immunodetectable CYP1A content showed the same trend as EROD activity, and the turnover number (nmol product formed/min/nmol CYP1A) for EROD activity was about the same in all groups, indicating that concentration of the catalyst alone could account for the different patterns of microsomal activity. CYP1A mRNA content was again induced to a similar degree by BNF in both the 6 and the 16 degrees C fish; the apparent half-life of the mRNA was substantially longer in cold-acclimated than in warm-acclimated BNF-treated fish. Comparing the levels of CYP1A mRNA and protein at the two acclimation temperatures following BNF treatment indicates that translational activity, rather than transcriptional activity, is the sensitive point in the effect of temperature on CYP1A induction in these fish.
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PMID:Effects of temperature acclimation on the expression of hepatic cytochrome P4501A mRNA and protein in the fish Fundulus heteroclitus. 144 51

Ebselen (PZ51) was tested for its ability to inhibit oxidative membrane damage and improve outcome of rabbit kidneys rendered cold ischaemic for 72 hr. In view of the rapid metabolism of ebselen, the antioxidant capacities of its two principal metabolites were first compared with that of the parent drug in an in vitro hepatic microsomal lipid peroxidation system initiated by NADPH/Fe(3+)-ADP. The potent antioxidant activity of ebselen was confirmed but metabolite I (2-glucuronylselenobenzanilide) exhibited no antioxidant potential up to a concentration of 50 microM; metabolite II (4-hydroxy-2-methyl-selenobenzanilide) did inhibit lipid peroxidation but was about 80 times less effective than the parent compound. The storage of rabbit kidneys in hypertonic citrate solution at 0 degrees for 72 hr of cold ischaemia resulted in greatly increased susceptibility to oxidative membrane damage in both the cortex and medulla as determined by the subsequent in vitro formation of two markers of lipid peroxidation (Schiff's bases and thiobarbituric acid-reactive material). Inclusion of ebselen (50 microM) in the flush and storage solution led to a highly significant reduction in these oxidative markers in both regions of the kidney. Intracellular and interstitial oedema was noted in organs subjected to 72 hr cold ischaemia and was reduced by ebselen (50 microM in the flush/storage solution). The rate of post-ischaemic lipid peroxidation was found to correlate well with the extent of oedema in the renal medulla (r = 0.84, P less than 0.001) but no such correlation was found in the cortex. Administration of ebselen (5.5 mg/kg i.v. and 100 microM in the flush/storage solution) did not improve the long-term survival of rabbits following autotransplantation of a single kidney stored for 48 or 72 hr. No protective effect of ebselen could be demonstrated either in terms of graded physiological function or histological outcome.
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PMID:Ebselen. Antioxidant capacity in renal preservation. 161 Mar 99


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