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)

The inducible 3-ketosteroid-delta 1-dehydrogenase of Nocardia corallina which catalyzes the introduction of a double bond into the position of carbon 1 and 2 of ring A of 3-ketosteroid has been obtained in four steps with a 50% yield and 360-fold purification. The enzyme is homogeneous as judged by SDS-gel electrophoresis and is a monomeric protein with a molecular weight of 60,500. The isoelectric point of the enzyme is about 3.1. The enzyme contains 1 mol of flavin adenine dinucleotide per mol of protein, and has a typical flavoprotein absorption spectrum with maxima of 458, 362 and 268 nm. The enzyme is very stable in the absence of added cofactors, and catalyzes the dehydrogenation of delta 4-3-ketosteroids in the presence of phenazine methosulfate, which acts as an excellent electron acceptor. Potassium ferricyanide and cytochrome c did not act as electron acceptors. The delta 1-dehydrogenation was also stimulated by molecular oxygen with stoichiometric production of hydrogen peroxide and delta 1,4-3-ketosteroid. The optimum pH is 10 for dehydrogenation using phenazine methosulfate, and is between 8.5 and 10 for the oxidase reaction. The enzyme oxidizes a wide variety of 3-ketosteroids, but not 3 beta-hydroxysteroids. 3-Ketosteroids having an 11 alpha- or 11 beta-hydroxyl group were oxidized at slow rates. The purified enzyme catalyzes efficiently aromatization of the A-ring of 19-nortestosterone and 19-norandrostenedione to produce estradiol and estrone. 19-Hydroxytestosterone, 19-hydroxyandrostenedion and 19-oxotestosterone were converted to the respective phenolic steroids with cleavage of the C10 side-chain. Activities of 3-ketosteroid-delta 4-dehydrogenase, delta 5-3-ketosteroid-4,5-isomerase, 3 beta-hydroxysteroid dehydrogenase and 17 beta-hydroxysteroid dehydrogenase were not observed in the purified preparations. Properties of this novel flavoprotein enzyme are discussed.
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PMID:Purification and characterization of 3-ketosteroid-delta 1-dehydrogenase from Nocardia corallina. 231 17

An NADPH-ferredoxin reductase (EC 1.6.7.1) was purified from bovine kidney mitochondria and its physicochemical properties were investigated. The ratio of the absorbances at 272 and 450 nm was 8.8, and the enzyme had a specific activity of 5,850 nmol/min/mg for the reduction of cytochrome c. We determined the molecular weights of the NADPH-ferredoxin reductase as 53,000 and 34,000 Da by SDS-PAGE and HPLC analysis, respectively. Renal ferredoxin was substituted by adreno-ferredoxin, but spinach ferredoxin was not. The reductase formed an immuno-precipitin line against antibody of the adrenal reductase on Ouchterlony double-diffusion analysis. The sequences of amino acid residues of this reductase in the amino-terminal regions were identical. The amino-terminal region of the reductase may thus play an essential role in the enzymatic function.
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PMID:Purification and characterization of NADPH-ferredoxin reductase from bovine kidney mitochondria. 235 62

Soluble cytochrome c-552 was purified from Thiobacillus ferrooxidans to an electrophoretically homogeneous state. The cytochrome showed absorption peaks at 276, 411 and 523 nm in the oxidized form and peaks at 315, 417, 523 and 552 nm in the reduced form. The molecular weight of the cytochrome was estimated to be 13,800 on the basis of the amino acid composition and heme content, and 14,000 from SDS-polyacrylamide gel electrophoresis analysis. Its midpoint redox potential at pH 7.0 was determined to be +0.36 V. The N-terminal amino acid sequence of the cytochrome was determined as follows: A-G-G-A-G-G-P-A-P-Y-R-I-S-?-D-?-M-V-?-S-G-M-P-G-. Ferrocytochrome c-552 was oxidized by the membrane fraction of T. ferrooxidans, and the oxidation rate was more rapid at pH 3.0 than at pH 6.5. Ferricytochrome c-552 was reduced by Fe(II)-cytochrome c oxidoreductase with Fe2+ at pH 3.5, while horse ferricytochrome c was not reduced by the enzyme under the same reaction conditions.
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PMID:Thiobacillus ferrooxidans cytochrome c-552: purification and some of its molecular features. 255 85

Cytochrome oxidase (CO) is a mitochondrial energy-generating enzyme used in brain studies as a marker of neural functional activity. The activity of CO in different brain regions, revealed histochemically, is distributed nonhomogeneously but in distinct patterns. Localized differences in CO activity could arise from localized differences in enzyme amount or from localized regulation of enzyme turnover number (molecular activity). To distinguish between these alternatives, we used antibodies against purified calf brain CO to assess the immunohistochemical distribution of CO amount (protein immunoreactivity) in several brain regions. Calf brain mitochondria (synaptic and nonsynaptic populations) were isolated from gray matter homogenates by differential centrifugation. CO was purified from detergent extracts of the mitochondria by cytochrome c-Sepharose 4B affinity chromatography. Antisera against the purified CO were raised in rabbits. The antibodies reacted specifically with CO, predominantly subunit IV, in SDS immunoblots. The antibodies did not react in SDS immunoblots with any other proteins solubilized from mitochondria or caudate nucleus but did cross-react with brain CO from other mammalian species and with bovine heart CO. The immunohistochemical distribution of CO amount matched the histochemical distribution of CO activity in all regions tested, including the monkey hippocampus and the mouse olfactory bulb, somatosensory (barrel) cortex, and cerebellum. Thus, the amount of CO in neural tissue is distributed in the same nonhomogeneous pattern as the histochemical activity of CO. The results suggest that mechanisms exist by which CO molecules are selectively distributed within neurons to meet local metabolic demands posed by neural functional activity.
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PMID:Brain cytochrome oxidase: purification, antibody production, and immunohistochemical/histochemical correlations in the CNS. 255 58

We have purified to homogeneity the regions derived by chymotryptic digestion of the ox neurofilament polypeptides NFH and NFM; the regions, called M1 and M2, are thought to form part of the projecting sidearms of mammalian neurofilaments [Chin, Eagles & Maggs (1983) Biochem. J. 215, 239-252]. They were isolated and purified under non-denaturing conditions and showed no tendency to interact with each other in solution. The Mr values obtained by sedimentation are approx. 61,000 for M1 and 42,000 for M2, considerably lower than the values obtained by SDS/polyacrylamide-gel electrophoresis. These Mr values were unchanged in the presence of 6 M-guanidine hydrochloride, suggesting that the regions exist as monomers in solution. Both M1 and M2 are highly phosphorylated, and there is only a slight change in the sedimentation value upon dephosphorylation. Dephosphorylation of M1 with alkaline phosphatase was more than 90% efficient but was never absolute. Dephosphorylation of M2 was complete. Both M1 and M2 bind Ca2+; in the case of M1, this binding is phosphorylation-dependent. M1 also binds cytochrome c, and dephosphorylation affects binding. In similar conditions, neurofilaments bind at least twice their own mass of cytochrome c, owing to their opposite net charges. No interactions were observed between native or dephosphorylated M1 and M2, and intact neurofilaments under a wide variety of conditions. These results are discussed in terms of the possible roles that neurofilament sidearms might play and throw doubt upon their supposed function of rigidly cross-linking neurofilaments together within the axoplasm of neurons.
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PMID:Characterization of two proteolytically derived soluble polypeptides from the neurofilament triplet components NFM and NFH. 255 34

The monoclonal antibody A2B4-2 has been shown to bind to the antigen receptor on the cloned pigeon cytochrome c-specific T cell hybrid, 2B4. Initial immunoprecipitation and SDS-PAGE analysis with this clonotypic antibody demonstrated that the antigen receptor on this cell had a m.w. of 85,000 to 90,000. Under reducing conditions, the receptor protein appeared as two bands of 45,000 to 50,000 and 40,000 to 44,000 on an SDS-PAGE gel. In this paper the antigen receptor on this T cell hybrid is further characterized. The molecule is shown to be a heterodimer that exists in two different forms on the cell surface. Receptor molecules with an apparent m.w. of 84,000 and 86,000 were isolated by immunoprecipitation and separation on polyacrylamide gradient gels. After reduction, the individual alpha- and beta-chains were separated by isoelectric focusing. In both forms of the receptor, the acidic alpha-chain had an apparent m.w. of 42,000 to 44,000. This alpha-chain associated with one of two forms of beta-chain. One beta-chain had a m.w. of 42,000 to 44,000, with a pI range of 7.5 to 7.9, and the alternate form of the beta-chain, beta', had a m.w. of 46,000 to 48,000 and a more acidic pI range of 6.5 to 7.5. The results of this investigation indicate that under reducing conditions on SDS-PAGE gels, the original upper 45,000 to 50,000 m.w. band represented beta'-chains alone, whereas the lower 40,000 to 44,000 m.w. band represented a mixture of alpha- and beta-chains. Additional data are presented to indicate that this heterodimeric protein has intrachain as well as interchain disulfide bonds. This conclusion was reached from the characteristic pattern of protein migration on SDS-PAGE gels in the presence of a reducing agent concentration gradient. Thus, both chains of the antigen receptor must have intrachain disulfide bonds and may have similar domain structures.
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PMID:An analysis of the structure of the antigen receptor on a pigeon cytochrome c-specific T cell hybrid. 257 44

The interaction between horse heart cytochrome c and Chromatium vinosum flavocytochrome c-552 was studied using the water-soluble reagent 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC). Treatment of flavocytochrome c-552 with EDC was found to inhibit the sulfide: cytochrome c reductase activity of the enzyme. SDS gel electrophoresis studies revealed that EDC treatment led to modification of carboxyl groups in both the Mr 21 000 heme peptide and the Mr 46 000 flavin peptide, and also to the formation of a cross-linked heme peptide dimer with an Mr value of 42 000. Both the inhibition of sulfide: cytochrome c reductase activity and the formation of the heme peptide dimer were decreased when the EDC modification was carried out in the presence of cytochrome c. In addition, two new cross-linked species with Mr values of 34 000 and 59 000 were formed. These were identified as cross-linked cytochrome c-heme peptide and cytochrome c-flavin peptide species, respectively. Neither of these species were formed in the presence of a cytochrome c derivative in which all of the lysine amino groups had been dimethylated, demonstrating that EDC had cross-linked lysine amino groups on native cytochrome c to carboxyl groups on the heme and flavin peptides. A complex between cytochrome c and flavocytochrome c-552 was required for cross-linking to occur, since ionic strengths above 100 mM inhibited cross-linking.
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PMID:The use of a water-soluble carbodiimide to study the interaction between Chromatium vinosum flavocytochrome c-552 and cytochrome c. 300 55

Cytochrome c oxidase was isolated from human hearts and separated by SDS gel electrophoresis. The identity of polypeptide bands with known subunits was demonstrated by immunoblotting with monospecific antisera to rat liver cytochrome c oxidase subunits. The polarographically determined kinetics of cytochrome c oxidation were similar to those reported for the bovine heart enzyme.
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PMID:Isolation and characterization of human heart cytochrome c oxidase. 301 29

The ubiquinol-cytochrome c oxidoreductase (bc1 complex, EC 1.10.2.2) has been isolated from the heart mitochondria of beef, chicken, turkey, duck and tuna with an identical procedure. The polypeptide composition of the different complexes, compared using SDS-polyacrylamide gel electrophoresis, shows that the three subunits carrying the prosthetic groups of the enzyme are highly conserved in all species. Also the large subunits I and II (core proteins) and band VI appear to be conserved in structure, while subunits VII and VIIa show a most remarkable structural variation in the various complexes. The steady-state ubiquinol-cytochrome c reductase analysis of the active enzymes indicates that all the bc1 complexes follow essentially a ping-pong mechanism, with the cytochrome c substrate displaying a partial competitive inhibition vs the ubiquinol substrate. The cytochrome c specificity of the reductase activity clearly is different in the various bc1 complexes, whereas the quinol specificity appears to be identical in all the enzymes.
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PMID:Comparative biochemistry of the ubiquinol-cytochrome c oxidoreductase (EC 1.10.2.2) isolated from different heart mitochondria. 302 4

A homobifunctional cleavable crosslinking reagent containing a selenoethylene group in the linker, and related reagents, have been synthesized and tested in a model system involving formation of a complex between albumin and cytochrome c. Functionally, complex formation was suggested by albumin inhibition of the ascorbate reduction of cytochrome c. Structurally, complex formation was demonstrated by crosslinking and subsequent separation of crosslinked complex from non-crosslinked proteins by SDS-polyacrylamide gel electrophoresis. The crosslinks were found to be cleavable by mild oxidation with low concentrations of periodate or with N-chlorobenzenesulfonamide immobilized on polystyrene beads (Iodo-Beads).
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PMID:Protein crosslinking reagents containing a selenoethylene linker are cleaved by mild oxidation. 302 3


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