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1.
Evidence for the occurrence of calmodulin in the yeasts Candida albicans and Saccharomyces cerevisiae 总被引:5,自引:0,他引:5
The lectin extracted from Vicia graminea seeds has been purified by conventional techniques but such procedures did not give a satisfactory yield. We describe a new purification which involves 3 steps after obtention of the crude extract. The first step is based on affinity chromatography on con A—Sepharose. Further purification steps were performed on DEAE-Sephacel chromatography and ultrogel AcA44 gel filtration. The homogeneity of the lectin was demonstrated by polyacrylamide gel electrophoresis. Purification of the lectin by this new method was less time consuming, the yield was higher and the specific activity increased. 相似文献
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L Fiume A Mattioli C Busi P G Balboni G Barbanti-Brodano J De Vries R Altmann T Wieland 《FEBS letters》1980,116(2):185-188
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Mild proteolysis by trypsin activates the purified (Ca2+ + Mg2+) - ATPase protein from human red cells in a way which is similar to the effect obtained by addition of calmodulin. The trypsin concentration required to reach half maximal effect in 3 minutes at 37°C is 2.5 – 3.5 μg/ml. SDS-poly-acrylamide gel electrophoresis reveals a degradation of the main protein (150'000 Dalton) into a large fragment (95'000 – 100'000 Dalton) and a small fragment (35'000 – 40'000 Dalton). Increasing ATPase activity correlates with the degree of proteolysis.The
Ca of the digested (Ca2+ + Mg2+)-ATPase is 0.85 ± 0.1 μM Ca2+ as compared to 8.0 ± 0.75 μM Ca2+ before digestion and is statistically significantly different from
Ca = 1.66 ± 0.22 μM Ca2+ observed in activation by a saturating calmodulin concentration. Addition of calmodulin to the trypsinized enzyme has neither an effect on the Ca2+-affinity nor achieves any large increase of the maximal rate.High Ca2+ concentrations (above 0.05 – 0.1 mM) after trypsin treatment still inhibit the (Ca2+ + Mg2+)-ATPase activity. Mg2+ activates in the same concentration range (
Mg = 25 μM) as in the undigested preparation (
Mg = 27 μM) and retains its competitive behaviour towards Ca2+ after trypsin treatment.It is concluded that (1) trypsin treatment unmasks high affinity sites for Ca2+ (
Ca 1 μM) and that, therefore, such sites are not added to the system by calmodulin, and (2) that inhibition by high Ca2+-concentrations is not due to Ca - Mg competition at sites located on the calmodulin molecule. 相似文献
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All-trans retinoic acid increased the incorporation of D-[3H]galactose into particulate and soluble glycoproteins in the epidermis of cultured pig skin slices nearly two-fold. Increased incorporation of D-[3H]galactose was not blocked by tunicamycin. This effect was specific for D-[3H]galactose since the incorporation of D-[3H]glucosamine and L-[14C]leucine into epidermal glycoproteins was unaffected by all-trans retinoic acid. All-trans retinoic acid and 13-cis retinoic acid had quantitatively similar effects on D-[3H]galactose incorporation. All-trans retinyl acetate and an aromatic retinoic acid analogue (‘Etretinate’) were less effective. SDS polyacrylamide gel electrophoresis and fluorography showed increased incorporation of D-[3H]galactose into all epidermal glycoproteins in the presence of all-trans retinoic acid. There was no evidence for synthesis of new glycoproteins such as mucins. 相似文献
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Resolutions and identification of the core deoxynucleoproteins of the simian virus 40 总被引:37,自引:0,他引:37
R S Lake S Barban N P Salzman 《Biochemical and biophysical research communications》1973,54(2):640-647
Low molecular weight basic core proteins of SV40 are resolved by Tris-Acetate-SDS polyacrylamide gel electrophoresis into a minimum of four polypeptides. These are the electrophoretic counterparts of the evolutionarily conserved histones F3, F2b, F2a2, and F2a1. Host African green monkey kidney cells contain an active protease activity which readily cleaves histone F3 during nuclear isolation in hypotonic buffers. 相似文献
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Genetic control of pigment-protein complexes I and Ia of the plastid mutant en:alba-1 of Antirrhinum majus 总被引:5,自引:0,他引:5
Herrmann F 《FEBS letters》1971,19(3):267-269
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Identification of an Escherichia coli inner membrane polypeptide specified by a lambda-tonB transducing. 总被引:1,自引:0,他引:1
Analysis by polyacrylamide gel electrophoresis of the proteins coded by a λB transducing phage, after infection of UV-irradiated bacteria, revealed the presence of at least 7 new polypeptides. Three of these were identified as proteins of the operon whilst three others were deleted by a spontaneous mutation in the B region carried by the phage. A single polypeptide, molecular weight 40,000 was absent from a phage carrying a proflavine induced mutation in B. We conclude that this protein, which was localised in the inner membrane by sarkosyl fractionation of the envelope, is the product. 相似文献
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J Goodson T S Pope J B Allred 《Biochemical and biophysical research communications》1984,122(2):694-699
Monomeric [14C] methyl avidin was shown to bind to sodium dodecyl sulfate-denatured biotinyl proteins and remain bound through polyacrylamide gel electrophoresis which allowed their detection by fluorography. This method was used to show that purified rat liver acetyl CoA carboxylase contained two high molecular weight forms of the enzyme (MR = 241,000 and 252,000) while rapidly prepared, crude rat liver cytoplasm contained two larger molecular weight (MR = 257,000 and 270,000) forms. Thus, the enzyme had undergone substantial proteolysis during purification. The crude enzyme preparation also contained a smaller biotinyl protein (MR = 141,000) which is likely a proteolytic product of the larger forms of acetyl CoA carboxylase. 相似文献
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Insulin in rat adipose tissue acts to increase the phosphorylation about 2.5-fold of a low molecular weight protein in the cytosol designated phosphoprotein m. Isoproterenol had no effect on the phosphorylation of phosphoprotein m. Some of the properties of phosphoprotein m are: soluble in 1% trichloro acetic acid, heat-stable and has a molecular weight of 23,000 on polyacrylamide gels in the presence of sodium dodecyl sulfate. Phosphoserine and phosphothreonine are the phosphorylated amino acid residues of phosphoprotein m. The physical and chemical properties of phosphoprotein m are similar to those of previously described inhibitor and modulator proteins. 相似文献
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The contents of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) in plasma and intestinal mucose were increased by dietary calcium and by dietary phosphorus restriction. The concentration of intestinal occupied receptors for 1,25(OH)2D3 was higher in calcium-restricted birds. The affinity (association constant) of intestinal receptors for 1,25(OH)2D3 was lower in phosphorus-restricted chicks, as compared to control or calcium-restricted chicks. The number of binding sites were not influenced by dietary calcium or phosphorus restriction. 相似文献
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Ulf Ljungberg Christer Jansson Bertil Andersson Hans-Erik Åkerlund 《Biochemical and biophysical research communications》1983,113(3):738-744
Photosystem II thylakoid particles possessing high rates of oxygen evolution, were shown to have a very simple polypeptide composition. Upon washing of these particles with 250 mM NaCl the oxygen evolution was inhibited up to 80% concomitant with a release of two polypeptides of 23 and 16 kDa. Readdition of the pure 23 kDa protein to the depleted thylakoids under low ionic strength reconstituted more than half of the lost activity. No stimulation was obtained with the 16 kDa protein alone or in combination with glycerol. The results give further strong evidence that the 23 kDa protein is an essential component in the oxygen evolving complex. The possible involvement of other proteins in this complex is discussed in light of the demonstrated simple polypeptide pattern of the photosystem II particles. 相似文献