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)

1. Nitrogenase activity of a strain of Azotobacter chroococcum lacking the structural genes of Monitrogenase (nifHDK) was associated with a V + Fe-containing protein and an Fe-containing protein [Robson, Eady, Richardson, Miller, Hawkins & Postgate (1986) Nature (London) 322, 388-390; Eady, Robson, Richardson, Miller & Hawkins (1987) Biochem. J. 244, 197-207]. 2. The Fe protein was purified to homogeneity by the criterion of Coomassie Blue staining after electrophoresis in 10% or 17% (w/v) polyacrylamide gels in the presence of SDS. One type of subunit, of Mr 32,000 +/- 2000, was found. 3. The native protein had an Mr of 62,500 +/- 2500 and contained approximately 4 Fe atoms and 4 acid-labile sulphide groups per molecule. The amino acid composition was similar to those of other purified Fe proteins, and, characteristically, tryptophan was absent. The specific activities (nmol of protein/min per mg of protein) when assayed under optimum conditions with the VFe protein from this strain were 1211 for H2 evolution under Ar, 337 for NH3 from N2 formation and 349 for C2H2 reduction. Activity of the Fe protein was O2-labile with a t1/2 of 36 s in air. At low temperatures the dithionite-reduced protein exhibited e.p.r. signals consistent with the presence of both S = 1/2 and S = 3/2 spin states. These signals were similar to those given by other nitrogenase Fe proteins, as were the changes in their line shape that occurred in the presence of MgATP or MgADP. The absorbance spectra showed that an increase in absorption occurred in the visible range on reversible oxidation of the dithionite-reduced protein. The oxidized-minus-reduced epsilon 420 was 6000 M-1.cm-1.
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PMID:The vanadium nitrogenase of Azotobacter chroococcum. Purification and properties of the Fe protein. 285 77

When cytochrome c oxidase is incubated at 43 degrees C for approximately 75 min in a solution containing the zwitterionic detergent sulfobetaine 12, the CuA site is converted into a type II copper as judged by changes in the 830-nm absorption band and the EPR spectrum of the enzyme. SDS-PAGE and sucrose gradient ultracentrifugation indicate concomitant loss of subunit III and monomerization of the enzyme during the heat treatment. Comparison of the optical and resonance Raman spectra of the heat-treated and native protein shows that the heme chromophores are not significantly perturbed; the resonance Raman data indicate that the small heme perturbations observed are limited to the cytochrome a3 site. Proton pumping measurements, conducted on the modified enzyme reconstituted into phospholipid vesicles, indicate that these vesicles are unusually permeable toward protons during turnover, as previously reported for the p-(hydroxymercuri)benzoate-modified oxidase and the modified enzyme obtained by heat treatment in lauryl maltoside. The sulfobetaine 12 modified enzyme is no longer capable of undergoing the recently reported conformational transition in which the tryptophan fluorescence changes upon reduction of the low-potential metal centers. Control studies on the monomeric and subunit III dissociated enzymes suggest that the disruption of this conformational change in the heat-treated oxidase is most likely associated with perturbation of the CuA site. These results lend support to the suggestion that the fluorescence-monitored conformational change of the native enzyme is initiated by reduction of the CuA site [Copeland et al. (1987) Biochemistry 26, 7311].
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PMID:Conversion of CuA to a type II copper in cytochrome c oxidase. 285 58

The absorbance and fluorescence spectral properties of mitochondrial F1-ATPase confirm that this protein does not contain tryptophan residues and therefore its fluorescence is due to tyrosines. The 36% increase in the fluorescence and the almost 100% increase in quantum yield upon denaturation of the protein suggest that a considerable number of tyrosyl residues have a very low quantum yield in the native enzyme. Quenching experiments using iodide indicate that all of the fluorophores are quenched and also all of them with the same quenching constant. These observations are interpreted as confirmatory of what has been found with several other proteins whose fluorescence originates from tyrosyl residues, where the buried tyrosines fluoresce with a much lower quantum yield than those which are exposed. ATP added to F1 previously depleted of loosely bound nucleotides changes the quenching constant of iodide and the quantum yield and this is interpreted to be due to a conformational change induced by the binding of the nucleotide to the enzyme. Addition of 2-mercaptoethanol decreases, although slightly, the polarization of the fluorescence. However, SDS addition gives a much bigger decrease. Hence disulphide bridges are less important for the tertiary structure of the protein than hydrophobic interactions, hydrogen bonding or other forces. Nevertheless the conformational change induced by reduction of disulphide bridges is detected in iodide quenching experiments and the change of the quantum yield of the enzyme.
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PMID:Structural studies of mitochondrial coupling factor 1 using tyrosine fluorescence. 286 Nov 23

Lethal and hemolytic toxins were purified by acetone precipitation, Sephadex G-50, CM-cellulose and CM-Sephadex column chromatography from the tentacles and bodies of the sea anemone Actinia equina. The isolated toxins, with a mol. wt of 19,000 determined by SDS-polyacrylamide gel electrophoresis, differed only slightly in amino acid composition and had a high tryptophan content. The isoelectric points were estimated to be 9.8 for equinatoxin I and 10.5 for equinatoxins II and III. The pure toxins exhibited high lethal potency; the acute i.v. LD50 in mice of equinatoxins I, II and III were 23, 35 and 83 micrograms/kg, respectively. The sigmoidal time course of hemolysis is characteristic of toxins.
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PMID:Isolation and characterization of three lethal and hemolytic toxins from the sea anemone Actinia equina L. 290 87

We have previously demonstrated that the alpha'-chain of human activated form of the fourth (C4b) and third (C3b) component of C are cleaved by plasma or serum from vertebrate species spanning through 300,000,000 yr of evolution yielding fragments identical with those obtained with human plasma. In this study, we investigated the molecular basis of this reaction. We chose barred sand bass plasma because this is the most primitive species analyzed possessing these activities. Barred sand bass plasma proteins were separated on a Sephadex G-200 column and the eluted samples analyzed for C4b and C3b cleavage. Individual fractions were inactive, but degradation was obtained when proteins of 380 and 155 kDa were combined. In contrast to the human regulatory proteins, the sand bass proteins require Ca2+ ions. K76COOH, an inhibitor of human factor I, inhibited the function of the 155-kDa but not of the 380 kDa-fraction. Thus it appears that the 155-kDa fraction functions as the C4b/C3b cleaving enzyme (I) and the 380-kDa material as its cofactor. Further purification of the 380-kDa fraction yielded a protein that by SDS-PAGE consisted of two noncovalently linked subunits of 110 and 42 kDa at a molecular ratio of 2:1. These two chains were antigenically distinct, and constitute domains of the same protein. The 110-kDa peptide binds C4b and not C3b but it fully expresses the cofactor function for the 155-kDa fraction on the cleavage of both C4b and C3b. Limited tryptic digestion of the 110-kDa domain demonstrated C4b binding activity in fragments of 34, 25, and 23 kDa. The activity of the 34-kDa fragment was the same as that of the undigested protein. Comparison of the amino acid composition of the barred sand bass cofactor and of human C4bp shows similar high content of cysteine and proline but not of tryptophan. It differs from human factor H in cysteine, serine, proline, and tryptophan. These studies indicate that regulatory proteins for the C4b and C3b C fragments may have appeared very early phylogenetically.
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PMID:Phylogeny of regulatory proteins of the complement system. Isolation and characterization of a C4b/C3b inhibitor and a cofactor from sand bass plasma. 291 26

The calf lens proteins gamma-II, -III and -IV crystallin have been photolyzed in pH 7.5 phosphate buffer solution at 25 degrees C. The photolysis light source was either a xenon arc lamp/monochromator system set to pass 290 +/- 5 nm or a nitrogen laser operating at 337.1 nm. Photolysis experiments at 337.1 nm were done both in the presence and absence of added 1.0 x 10(-4) M N-formylkynurenine (NFK). In addition, 1 x 10(-5) M riboflavin was added as a photosensitizer in a few of the experiments. All solutions were 1.0 mg ml-1 protein, and 1.0 ml of solution was irradiated for periods ranging from 10 min to 3 hr. During the 337.1 nm irradiations, the turbidity of the protein solutions was continuously monitored using a He-Ne laser at 632.8 nm. Progress of the 290 nm irradiations was monitored by observing the loss of tryptophan fluorescence for each of the gamma crystallin proteins. The rate of growth of light scattering, upon 337.1 nm irradiation, was greatest for gamma-IV. Addition of NFK caused the rates of growth of UV-induced light scattering of all three gamma crystallins to increase significantly. These rates were in the order: gamma-IV much greater than gamma-III greater than gamma-II. Following UV exposure, the protein solutions were analyzed using UV-visible absorption spectroscopy and SDS-PAGE. Irradiated gamma crystallin solutions showed increased optical density throughout the visible region, resulting from solution turbidity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Light scattering and photocrosslinking in the calf lens crystallins gamma-II, III and IV. 292 21

A set of four proteins, termed calcimedins, are isolatable from smooth, cardiac and skeletal muscle by using a fluphenazine-Sepharose affinity column. The calcimedins show apparent Mr values of 67,000, 35,000, 33,000 and 30,000 by SDS/polyacrylamide-gel electrophoresis. The 67,000-Mr calcimedin (67 kDa calcimedin) has now been purified to homogeneity by using DEAE-cellulose chromatography followed by Ca2+-dependent binding to phenyl-Sepharose. The amino acid analysis of the 67 kDa calcimedin shows this protein does not contain trimethyl-lysine but does contain 2 mol of tryptophan/mol of protein. The 67 kDa calcimedin shows positive ellipticity in the near-u.v. range with c.d. Ca2+-binding studies indicate one high-affinity Ca2+-binding site with Kd 0.4 microM. The data show that the 67 kDa calcimedin is distinct from other Ca2+-binding proteins described to date.
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PMID:67 kDa calcimedin, a new Ca2+-binding protein. 294 95

Albumin samples from three species (avian, bovine and human) were electrophoresed on gradient polyacrylamide gels in the presence of sodium dodecyl sulphate (SDS-PAGE). The resulting electrophoregram from each sample of serum albumin investigated showed multiple protein bands of a wide range of molecular weights. All seven samples of human serum albumin were found, using gel immunodiffusion, to be contaminated with other proteins. All but one sample was contaminated with proteins such as haptoglobin, alpha 1-glycoprotein, alpha 1-trypsin inhibitor, and prealbumin. This contamination accounts for part of the heterogeneity of these samples. Immunoblots, where the proteins were transferred to nitrocellulose and incubated with antisera, gave a better demonstration of the heterogeneity than Coomassie Blue staining and the immunoblotting procedure appeared to be more sensitive than the gel immunodiffusion technique. The heterogeneity of serum albumin demonstrated by the former technique included that of the monomer which was shown to be contaminated with antithrombin III. The commercial samples of human serum albumin, claimed as pure, were found to vary greatly in their tryptophan content, which also indicated heterogeneity. Heat treatment of human serum albumin with 1% SDS, followed by chromatography on agarose, removed the protein contaminants and with it the tryptophan. The presence of tryptophan in human serum albumin, therefore, indicated the presence of impurities.
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PMID:Further evidence for the heterogeneity of serum albumin. 309 19

Bovine brain tau protein (tau) consists of four closely related phosphoproteins named tau 1, tau 2, tau 3 and tau 4, that range in size from 55 to 68 kDa (as determined by gel electrophoresis). Here we report an improved large-scale purification method for tau protein and the separation of the four individual tau protein species. The separation of the individual tau protein was accomplished by two chromatographic techniques: hydroxyapatite chromatography allowed the separation of two pairs of tau protein (tau 1 and tau 3) and (tau 2 and tau 4); fast protein liquid chromatography on a Mono Q column at basic pH achieved the resolution of the individual tau protein species in each pair derived from hydroxyapatite columns. Chromatography on the Mono Q column revealed that tau protein possesses previously unrecognized, highly reactive sulfhydryl groups that may oxidize to form intermolecular disulfide bridges. The isolation of individual species of tau in substantial quantities permitted an improved amino acid analysis that demonstrated the occurrence of cysteine and tryptophan in the protein. The availability of individual tau protein species greatly simplified the analysis for mode II phosphorylation of tau, which was found to be catalyzed by the calcium/phospholipid-dependent protein kinase C. The mode II phosphorylation of tau by protein kinase C was not associated with a mobility shift for tau protein in SDS-polyacrylamide gel electrophoresis, in contrast to mode I phosphorylation of tau by the Ca2+/calmodulin-dependent kinase, which produces a substantial shift in mobility.
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PMID:Separation of the different microtubule-associated tau protein species from bovine brain and their mode II phosphorylation by Ca2+/phospholipid-dependent protein kinase C. 312 2

A new macromolecular antibiotic C-1027 was obtained from the broth filtrate of Streptomyces globisporus C-1027 by precipitation with ammonium sulfate, DEAE-cellulose column chromatography and gel filtration chromatography on a Sephadex G-75 column. This antibiotic, prepared as a white powder, is an acidic polypeptide having an isoelectric point of pH 3.5-3.7 and a molecular weight of 15,000 as determined by SDS-polyacrylamide gel electrophoresis and gel filtration chromatography. The acid hydrolysate of the purified antibiotic C-1027 contained no methionine or tryptophan. From the physico-chemical data, it may be considered to possess a very labile non-protein chromophore.
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PMID:A new macromolecular antitumor antibiotic, C-1027. II. Isolation and physico-chemical properties. 319 92


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