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Query: UMLS:C0272170 (SDS)
 50,377 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The alkaline phosphatase present on isolated brush border and basal lateral membranes of rat duodenal epithelium were examined by means of a variety of biochemical assays and physical methods. The two alkaline phosphatases have similar pH optima of 9.6--9.8, similar substrate km's for p-nitrophenyl phosphate (PNPP) of 71 micromolar, similar responses to the inhibitors 2-mercaptoethanol, theophylline, phenylalanine, and ethylenediaminetetraacetic acid (EDTA), similar sensitivities to calcium, magnesium, zinc, sodium, and potassium, and similar insensitivities to digestion with trypsin of papain. The two enzymes also exhibit similar molecular weights on SDS-polyacrylamide gels in the range 124,000--150,000, and both enzymes show an Rf value of 0.092 on Triton X-100 polyacrylamide gels, indicating similar intrinsic charges. The Vmax of the brush border enzyme is ten times greater than that of the basal lateral enzyme, 140 mumoles/mg-h as opposed to 14 mumoles/mg-h. The differences in Vmax are a reflection of the known distribution of alkaline phosphatase in rat duodenum, there being more alkaline phosphatase activity present on the brush border than on the basal lateral surface. One other major difference was observed between the two enzymes, the stimulation of the basal lateral and not the brush border alkaline phosphatase by SDS, Triton X-100, or cholate. We conclude that the enzymes are very similar to one another and probably perform similar membrane functions.
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PMID:Alkaline phosphatase of basal lateral and brush border plasma membranes from intestinal epithelium. 4 35

In the outer membrane of P. aeruginosa, a protein of apparent molecular weight 8,000 (protein I) is present as a major protein. Purification and chemical analysis of protein I were carried out. This protein was purified by essentially the same procedure as for the purification of the E. coli lipoprotein, which was developed by Inouye et al. (J. Bacteriol. (1976) 127, 555--563). The amino acid composition of protein I was determined. Protein I lacks proline, valine, isoleucine, phenylalanine, tryptophan, and half-cystine. Fatty acid analysis of the protein revealed that it contained 0.89 mol of fatty acids per mol of protein. Among the fatty acids hexadecanoic acid (C16:0) was predominant. In an in vivo labeling experiment, [2-3H]glycerol was incorporated into protein I. A protein with similar mobility to protein I on urea-SDS polyacrylamide gel electrophoresis was isolated from the purified peptidoglycan of P. aeruginosa by trypsin digestion. The amino acid composition of this protein was essentially the same as that of protein I. These results indicate that the outer membrane of P. aeruginosa contains a protein analogous to the E. coli lipoprotein, although considerable differences were observed in the amino acid composition and the fatty acid content.
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PMID:Isolation of characterization of a major outer membrane protein of Pseudomonas aeruginosa. Evidence for the occurrence of a lipoprotein. 10 84

Pyruvate kinase isolated from Neurospora and purified to homogeneity has been shown to be a tetramer of molecular weight around 242 000 by gel filtration studies and 239 000 daltons by sedimentation equilibrium measurements. The monomer produced by treatment with guanidine hydrochloride is found to be 51 000-52 000 daltons by sedimentation equilibrium studies; a molecular weight of 62 000 was determined for the monomer generated by SDS treatment by electrophoresis in SDS-polyacrylamide gels. The enzyme has an isoelectric point of 6.35-6.41; Substrate saturation kinetics of PEP show a variable extent of cooperativity depending upon the buffer ions employed in the assay. ADP is the most effective phosphoryl group acceptor, GDP and IDP being poor substitutes. A divalent cation, Mg-2+, is required for activity. At low concentrations, Ca-2+ acts as an activator of pyruvate kinase but it is inhibitory at high concentrations. Fructose 1,6-diphosphate is the most potent allosteric activator, fructose 6-phosphate being next in order of effectiveness. Valine is a powerful inhibitor. Phenylalanine, tyrosine, and tryptophan are without any effect individually, but their simultaneous presence results in a considerable activation. Alanine does not affect this enzyme appreciably.
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PMID:Subunit structure and some properties of pyruvate kinase of Neurospora. 12 21

Yeast cells (Saccharomyces cerevisiae) were grown in the presence of [14C]phenylalanine and pulse-labelled with [3H]phenylalanine in the presence of cycloheximide. The proteins extractable into chroloform: methanol (2:1) were isolated from mitochondria and analysed by SDS gel filtration. Four protein fractions varying in molecular weight were separated. In order to identify the transcriptional origin and the site of protein synthesis ethidium bromide was used. Different sensitivity of protein syntheses to various concentrations of ethidium was shown. These data are discussed in relation to the possible presence of two classes of membrane-bound polyribosomes in mitochondria.
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PMID:Intramitochondrial synthesis of membrane proteins in yeast: differential inhibition by ethidium. 32 93

Rates of protein synthesis by intact liver parenchymal cells isolated from male Fischer F344 rats ranging in age from 2.5 to 30 months were determined by measuring the incorporation of [3H] valine into acid-insoluble material and the specific activity of the extracellular valine. The rate of protein synthesis decreased 44% from 2.5 to 18 months and then increased slightly (18%) from 18 to 30 months. There was no dramatic change in the types of proteins synthesized by isolated liver parenchymal cells isolated from 2- or 18-month-old rats as determined by SDS-polyacrylamide gel electrophoresis. The ribosomal-transit time by liver parenchymal cells isolated from 18-month-old rats was 60% higher than the ribosomal-transit time of liver parenchymal cells isolated from 4-month-old rats. The fidelity of protein synthesis by parenchymal cells isolated from 4- and 18-month old rats was compared by measuring the incorporation of p-fluorophenyl alanine (an analogue of phenylalanine) into acid-insoluble material. Although protein synthesis decreased significantly from 4 to 18 months, the fidelity of protein synthesis remained constant.
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PMID:A comparison of protein synthesis by liver parenchymal cells isolated from Fischer F344 rats of various ages. 49 78

Rabbit skeletal alpha-tropomyosin, separated by hydroxyapatite chromatography, was treated with trypsin (1/100 wt/wt) at 0 degrees C for 24 h. Trypsin-resistant fragments of tropomyosin were separated into the precipitate and supernatant fractions at pH 4.3 in 1 M KCl, and these were subjected to QAE-Sephadex A50 column chromatography for further purification. SDS-gel electrophoresis showed 16,000 and 14,000 dalton bands for the supernatant (s-fragment) and an 11,500 dalton band for the precipitate (p-fragment). We obtained a 13,500 dalton chain (13,500 dalton fragment) in addition to the s- and p-fragments upon treatment with more dilute trypsin (1/500 wt/wt) for 48 h at 0 degrees C. Both the p- and 13,500 dalton fragment had the same C-terminal portion as intact alpha-tropomyosin, and could form an intra-chain disulfide bond on oxidation. Therefore, these two fragments were deduced to be polypeptides from some points on the N-terminal side of Cys 190 to the intact C-terminal. The s-fragment, on the other hand, did not contain any cysteine, Phe, or His residues according to amino acid analysis, suggesting that the fragment is derived from the N-terminal side from Cys 190. Tentative assignment of the fragments was carried out by amino acid analysis, and C- and N-terminal determination. The p-, s-, and 13,500 dalton fragments appear to be in coiled-coil form in solution, having alpha-helical contents of 77,71, and 64%, respectively, and are able to interact with intact tropomyosin to reduce the viscosity of tropomyosin solution. The s-, p-, and 13,500 dalton fragments have little binding capacity individually to troponin, but the mixture, i.e., the s- and p-fragments, the 13,500 dalton fragment and the N-chain, which was obtained by cleavage at Cys 190, showed clear binding with troponin independent of Ca2+ in solution as detected by gel electrophoresis. The p-fragment showed some binding to troponin, since cross-linkage to troponin was possible by treatment with dimethyl suberimidate. From the result, it can be inferred that the troponin binding regions in tropomyosin are located on both sides of Cys 190, where trypsin attacks more easily than at other parts of the molecule, leaving two trypsin-resistant fragments.
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PMID:Tropomyosin fragments obtained by tryptic digestion. 65 5

Protein 35/7.7 is an abundant cytosol protein of Morris hepatoma 3924A and Novikoff hepatoma which was not found in normal liver. Protein 35/7.7 was isolated from the cytosol of Novikoff hepatoma ascites cells by ammonium sulfate precipitation and DEAE-cellulose chromatography. It migrated as a single major spot on two-dimensional isoelectric focusing-SDS polyacrylamide gels. The N-terminal hexapeptide is Val-Asx-Pro-Thr-Val-Phe and its carboxyl-terminal amino acid is phenylalanine.
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PMID:Purification and partial characterization of protein 35/7.7 a cytosol protein that is abundant in rapidly growing hepatomas. 70 6

A procedure for the preparation of highly purified pig prothrombin is described. Compared to the initial clotting activity of the starting plasma, this protein was purified 776 times with a final yield of 8 per cent. The purified zymogen showed a specific activity of 1,460 NH units/mg of protein , a molecular weight of 65,000 as determined by SDS-polyacrylamide disc gel electroesis, E 1.0 mg/ml 1.0 cm, 280 nm = 1.45 at pH 7.0 and the following amino acid composition: Asx 51, Thr 38, Glx 62, Pro 23, Gly44, Ala 25, Half-Cys 30, Val 35, Met 3, Ile 30, Leu 32, Tyr 19, Phe 22, Lys 36, His 8, Arg 28, and Trp 13, which accounts for a minimum molecular weight of 59,370 (carbohydrates not computed). Alanine was found as the only N-terminal residue. Carboxypeptidases A and B failed to release any C-terminal residue. By hydrazinolysis however 0.4 mole of serine was released per mole of prothrombin. The activation of crude and chromatographed pig prothrombin was investigated.
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PMID:Pig prothrombin: purification and properties. 95 54

Troponin C was isolated from the skeletal muscle of bullfrog (Rana catesbeiana), and its relative molecular mass was estimated to be 18,000 by SDS/polyacrylamide gel electrophoresis. In its amino acid composition, bullfrog troponin C was similar to that of the frog (Rana esculenta) but different from that of rabbit. Its ultraviolet spectrum was consistent with its amino acid composition. The ultraviolet difference spectrum of the Ca(2+)-loaded form vs. the metal-free form indicated that the single Tyr residue and some Phe residues in the bullfrog troponin C molecule were affected by the conformational change associated with Ca2+ binding. On electrophoresis in polyacrylamide gel in 14 mM Tris and 90 mM glycine, the metal-free and Mg(2+)-loaded forms migrated slower than the Ca(2+)-loaded form. The property is shared by rabbit troponin C but not parvalbumins or calmodulin. The ATPase activity of CDTA-treated myofibrils reconstituted with bullfrog troponin C showed the same Ca(2+)- and Sr(2+)-sensitivity as that of those reconstituted with rabbit troponin C. Bullfrog troponin C is, thus, physiologically the same as rabbit troponin C, in spite of several marked differences in their physicochemical properties.
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PMID:Preparation and characterization of troponin C from bullfrog skeletal muscle. 129 89

As part of our study of isoenzyme forms of human cytochrome c oxidase, we purified subunit IV from human heart and skeletal muscle with reversed-phase HPLC and determined the N-terminal amino acid sequences and the electrophoretic mobility. The N-terminus of human heart subunit IV proved to be ragged with 30% of the protein lacking the first three residues. Also a Tyr/Phe polymorphism was observed at residue 16. No differences in N-terminal sequence and electrophoretic mobility were observed between subunit IV of cytochrome c oxidase from human heart and skeletal muscle. Therefore, our results suggest that identical subunits IV are present in cytochrome c oxidase from human heart and skeletal muscle. A putative isoform of subunit IV with a blocked N-terminus was purified from human heart cytochrome c oxidase, which proved to have a different retention time on a reversed-phase column and also a slightly higher electrophoretic mobility on an SDS-polyacrylamide gel compared to the native subunit IV. We could not demonstrate the existence of isoforms of subunit IV in human skeletal muscle.
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PMID:Subunit IV of human cytochrome c oxidase, polymorphism and a putative isoform. 131 8


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