Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0272170 (SDS)
 50,377 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

NADH dehydrogenase [EC 1.6.99.3] in membranes of Bacillus caldotenax was solubilized with sodium N-lauroylsarcosinate and purified 50-fold from membranes to 75-80% homogeneity, as judged by SDS-polyacrylamide gel electrophoresis. The enzyme was considered to be located on the electron transport chain and to be an FAD-containing protein. The molecular weight of the subunit was estimated to be 44,000. The enzyme (or the enzyme bound to the B. caldotenax membrane lipids) follows a ping-pong mechanism. The enzyme can oxidize NADH, but not NADPH, with 2,6-dichlorophenol indophenol, ferricyanide, menadione, and cytochrome c as electron acceptors. Membrane lipids or Triton X-100 stimulated the enzyme activity, except that with menadione. Lipids decreased the apparent affinity of electron acceptors and NADH to the enzyme, and increased the maximum velocity, except when menadione was used as the electron acceptor. Lipids partially protected the enzyme from thermal inactivation. The enzyme exhibited a continuous Arrhenius plot, while the lipids- or membrane-bound enzyme exhibited a discontinuous plot.
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PMID:Effect of lipids on a membrane-bound NADH dehydrogenase from Bacillus caldotenax. 616 6

The monoclonal antibody, A2B4-2, specifically bound to and inhibited antigen-induced IL-2 release from the cloned pigeon cytochrome c-specific T cell hybrid, 2B4. The initial immunoprecipitation with these reagents demonstrated a protein of 85-90kd on non-reducing conditions, and two bands of 45-50 and 40-44 on reducing conditions. These data enabled us to conclude that this monoclonal antibody bound to the antigen receptor on the 2B4 cell. In this paper we have presented results that further define the receptor structure. The migration pattern of the protein on SDS-PAGE in the presence and absence of reducing agents was consistent with the interpretation that the receptor has intrachain disulfide bonds that create globular domains. Sequence data from the recently described cDNA clones that encode receptor genes confirm that there are cysteine residues in positions that could be involved in such disulfide bonding. Since both alpha and beta chains behave identically on the SDS-PAGE we predict that both chains have the same double domain structure. The antigen receptor has a heterodimeric structure. A relatively simple acidic alpha chain is bound to one of two forms of the beta chain. Some of the receptors have a beta chain equal in molecular weight to the alpha chain, while some of the beta chains (beta') are heavier and more acidic. The difference in beta chain forms appears to be due to different levels of glycosylation of this chain. The cDNA sequence data demonstrate that there are several possible carbohydrate addition sites on the protein encoded by this gene so it may be that 2B4 beta chains are present that are either completely or partially glycosylated at these sites. Finally, we have presented a preliminary experiment that indicates that a smaller 20-25kd molecule is associated with the antigen receptor. The well characterized T3 molecule appears to be in a complex with the clonotypic structure on human T cells. The crosslinking data that we present suggests that a similar molecule may be present in the murine system.
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PMID:Characterization of the antigen-specific T cell receptor from a pigeon cytochrome c-specific T cell hybrid. 621 Feb 40

The membrane-bound cytochrome f-556.5 from the blue-green alga Spirulina platensis was purified to apparent homogeneity. Most of its properties are comparable to cytochrome f isolated from higher plants and green algae. It is clearly distinguishable from soluble cytochrome c-554, also present in Spirulina, which probably replaces the function of plastocyanin in photosynthetic electron transport. 1. The reduced form of cytochrome f exhibits an asymmetrical alpha-band with a maximum at 556.5 nm, and a pronounced shoulder at 550 nm. The beta-, gamma and delta-bands coincide with those described for Scenedesmus cytochrome f-553, with maxima at 524 (532), 422, 331 and a protein peak at 276 nm. The maximum of ferricytochrome f is at 410.5 nm; there is no indication of a weak 695 nm band, described for soluble c-type cytochromes. The purest preparations had a delta/protein-peak ratio of 0.8; the gamma/alpha ratio was 7.3. Formation of a pyridine hemochromogen with a maximum at 550 nm indicated a c-type cytochrome. The molar extinction coefficient at 556.5 nm is 30200, the differential extinction coefficient 21 500. 2. The molecular weight determined by gel filtration or SDS-polyacrylamide gel electrophoresis is 33 000 and 34 000, respectively. 3. The redox properties differ from those described for other cytochromes f isolated from green algae and higher plants: the midpoint redox potential is significantly more negative (+318 mV, pH 7.0) and from pH 6 to 10 no pH dependence is observed. 4. The isoelectric point was determined at pH 3.95, which is more acidic as compared to other cytochromes f. 5. Comparison of the amino acid composition indicated a distant relationship to higher plant cytochrome f and a closer relationship to cytochrome f from green algae.
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PMID:Purification and characterization of cytochrome f-556.5 from the blue-green alga Spirulina platensis. 625 70

The nitrogen-fixing, aerobic hydrogen-oxidizing bacterium Alcaligenes latus forms hydrogenase when growing lithoautotrophically with hydrogen as electron donor and carbon dioxide as sole carbon source or when growing heterotrophically with N2 as sole nitrogen source. The hydrogenase is membrane-bound and relatively oxygen-sensitive. The enzymes formed under both conditions are identical on the basis of the following criteria: molecular mass, mobility in polyacrylamide gel electrophoresis, Km value for hydrogen (methylene blue reduction), stability properties, localization, and cross-reactivity to antibodies raised against the 'autotrophic' hydrogenase. The hydrogenase was solubilized by Triton X-100 and deoxycholate treatment and purified by ammonium sulfate precipitation and chromatography on Phenyl-Sepharose C1-4B, DEAE-Sephacel and Matrix Gel Red A under hydrogen to homogeneity to a specific activity of 113 mumol H2 oxidized/min per mg protein (methylene blue reduction). SDS gel electrophoresis revealed two nonidentical subunits of molecular weights of 67 000 and 34 000, corresponding to a total molecular weight of 101 000. The pure enzyme was able to reduce FAD, FMN, riboflavin, flavodoxin isolated from Megasphaera elsdenii, menadione and horse heart cytochrome c as well as various artificial electron acceptors. The reversibility of the hydrogenase function was demonstrated by H2 evolution from reduced methyl viologen.
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PMID:Purification and properties of the membrane-bound hydrogenase from N2-fixing Alcaligenes latus. 630 22

Possible involvement of polypeptides of b-c1 complex of beef-heart mitochondria in its redox and protonmotive activity has been investigated, by means of chemical modification of amino acid residues in the soluble as well as in the phospholipid-reconstituted b-c1 complex. Treatment of the enzyme with tetranitromethane (C(NO2)4) or with ethoxyformic anhydride (EFA), that modify reversibly tyrosyl and hystidyl residues respectively, resulted in a marked inhibition of electron transport from reduced quinols to cytochrome c. This was accompanied, in b-c1 reconstituted into phospholipid vesicles, by a parallel inhibition of respiratory-linked proton translocation; the H+/e- stoichiometry remained unchanged. Treatment of b-c1 complex with DCCD, that specifically modifies carboxylic groups of glutammic or aspartic residues caused a marked depression of proton translocation in b-c1 vesicles, under conditions where the rate of electron flow in the coupled state, was enhanced. As a consequence the H+/e- stoichiometry was lowered. SDS gel electrophoresis and [14C]DCCD-labelling of the polypeptides of the b-c1 complex showed a major binding of 14C-DCCD to the 8-kDa subunit of the complex and possible cross-linking, induced by DCCD treatment, of polypeptide(s) in the 8-kDa band and the 12-kDa band, with the Fe-s protein of the complex, with the appearance of a new polypeptide band with an apparent molecular mass of about 40 kDa. Involvement of polypeptides of low molecular mass, for which no functional role was so far described, and possibly of the Fe-S protein in the redox-linked proton translocation in b-c1 complex is suggested.
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PMID:Redox-linked proton translocation in the b-c1 complex from beef-heart mitochondria reconstituted into phospholipid vesicles. Studies with chemical modifiers of amino acid residues. 631 24

Pigeon cytochrome c-specific, Ek beta:Ek alpha Ia molecule-restricted T cell hybrids were used as immunogens in order to obtain antisera and monoclonal antibodies directed against the antigen receptor. Antisera against 2 different T cell hybrids specifically altered the IL 2 release only from the immunizing clone. Monoclonal antibodies against one of these hybrids were also obtained. They specifically bound to and inhibited the IL 2 release only from the immunizing cell. Lectin-induced IL 2 release was not blocked by these monoclonals. Immunoprecipitation and SDS-PAGE analysis of detergent lysates from surface-labelled hybrid cells demonstrated a heterodimeric structure composed of chains of 45-50 and 40-44 kd apparent molecular weight. These chains were linked by disulfide bonds and each appeared to contain intramolecular disulfide bonds as well. The molecule that has been isolated is likely to be the receptor for antigen on the immunizing clone.
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PMID:The use of antisera and monoclonal antibodies to identify the antigen-specific T cell receptor from pigeon cytochrome c-specific T cell hybrids. 631 71

Three cytochrome c hydrolase species were found in the 0.05% SDS extract from submitochondrial particles. Their polypeptides all have a molecular weight of 17 000 but differ in pI values (4.0, 4.2 and 4.4), as shown by SDS-polyacrylamide gel electrophoresis and polyacrylamide gel isoelectric focusing. The activity of pooled cytochrome c hydrolases is sensitive to PMSF, pCMPS , and leupeptin but insensitive to EDTA or o-phenanthroline. Besides the cytochrome c-hydrolyzing enzymes, the SDS extract contains three protein components with BAPA ( BANA )-hydrolyzing activity, which also show similar molecular weights (17 5000) but different pI values (4.2, 4.3 and 4.7). It is supposed that at least some of the enzymes mentioned are involved in the intramembrane proteolysis of polypeptides synthesized on mitoribosomes .
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PMID:Detection, isolation and some properties of membrane proteinases from yeast mitochondria. 637 30

NADPH-dependent reduction of cytochrome c is catalyzed both by microsomes and the cytosolic fraction isolated from Trypanosoma cruzi homogenates. About one-third of the activity is microsomal and two-thirds is cytosolic. The microsomal activity is increased by Lubrol and sodium cholate, but pretreatment with phenobarbital has negligible effect. On the other hand, detergents do not affect the cytosolic activity but it is increased by phenobarbital. From these observations, it is concluded that the NADPH-dependent reduction of cytochrome c by microsomes and the cytosol corresponds to two distinct enzymes. The cytosolic enzyme has been purified to a single SDS-PAGE band of about 53,000 da and partially characterized.
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PMID:NADPH-cytochrome c reductases of Trypanosoma cruzi. 643 96

Our previous studies have shown that 2,2-dimethyl-5-t-butyl-1,3-benzodioxole (DBBD), a methylenedioxyphenyl (MDP) analog in which the methylene hydrogens have been replaced by methyl groups, does not form an inhibitory complex with cytochrome P-450 nor induce this cytochrome. However, in the present experiments, DBBD-treated male Dub:ICR mice showed an increase in NADPH-dependent cytochrome c (P-450) reductase and epoxide hydrolase activity. This separation of cytochrome P-450 induction from the induction of epoxide hydrolase and NADPH-dependent cytochrome c (P-450) reductase appears to be unique among inducers of xenobiotic metabolizing enzymes. In similar experiments, mice were treated with phenobarbital + DBBD or 3-methylcholanthrene + DBBD and the following parameters were measured: cytochrome P-450 content; NADPH-dependent reduction of cytochrome c; ethylmorphine and benzphetamine N-demethylase; 7-ethoxycoumarin O-deethylase; benzo[a]pyrene hydroxylase; and ethoxyresorufin O-deethylase. The microsomal proteins were examined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE). Phenobarbital + DBBD treatment gave results which did not differ significantly from those obtained with phenobarbital alone. In contrast, cytochrome P-450 content and benzo[a]pyrene hydroxylase and ethoxyresorufin O-deethylase activities were less in mice treated with 3-methylcholanthrene + DBBD than in animals treated with 3-methylcholanthrene alone. SDS-PAGE confirmed that induction of cytochrome P-450 by 3-methylcholanthrene was reduced by DBBD, suggesting that the latter compound may be an antagonist to the Ah cytosolic receptor.
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PMID:2,2-Dimethyl-5-t-butyl-1,3-benzodioxole: an unusual inducer of microsomal enzymes. 643 15

Previous experiments have shown that nerve growth factor (NGF) enhances regeneration of goldfish optic nerve after local application of NGF at the site of the lesion. However, the site and mechanism of action of NGF are not yet known. One possibility is that NGF is taken up at the site of the lesion and retrogradely transported to the cell bodies of the retinal ganglion cells and thereby exerts its trophic effects. The present work was carried out to assess the role of retrograde transport of NGF in this enhanced regeneration of goldfish retinal ganglion cells. In intact retinal ganglion cells of the goldfish, 125I-labeled NGF was found not to be retrogradely transported from the optic tectum to the retina, suggesting that retinal ganglion cells do not possess specific NGF receptors. However, if [125I]NGF was injected at the site of an optic nerve lesion at the time of lesion, [125I]NGF was retrogradely transported from the site of a lesion of the optic nerve to the cell body of retinal ganglion cells. The accumulated radioactivity was shown to be intact NGF by SDS-PAGE. The ability of NGF to decrease the time required for recovery of visual function was observed only when NGF was administered at the time of the injury. Likewise, no transport of [125I]NGF was observed when it was injected at the crush site 16 hr or longer after crush. Thus, there is a temporal correlation between the ability of intact [125I]NGF to be retrogradely transported from a lesion site to the retina and the regenerative effect of NGF. Autoradiography showed that the [125I]NGF accumulated only in retinal ganglion cells. The transport of NGF in the lesioned goldfish visual system was not specific for NGF in that other proteins (cytochrome c, bovine serum albumin) were transported equally well. Likewise, transport of [125I]NGF was not prevented by concomitant administration of excess unlabeled NGF. The retrograde transport of [125I]NGF therefore was not selective and did not appear to be mediated by specific NGF receptors in this system. This nonspecific transport of [125I]NGF did not occur in the axotomized spinal motor neurons in the neonatal or adult rat or in the newt. However, receptor-mediated transport is seen in lesioned sensory neurons in both species.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Retrograde transport of nerve growth factor in lesioned goldfish retinal ganglion cells. 663 75


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