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  • Biochemistry and Biotechnology  (7)
  • Buffer electrofocusing  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 14 (1993), S. 1295-1301 
    ISSN: 0173-0835
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: A DGE apparatus, made of Perspex, consisting of a separation column (5 × 2.2 cm) and containing a 0-4% linear Ficoll density gradient, was constructed. Only 2.5 cm of the column were used for high resolution separations. A specially designed removable top cone permitted precise gradient introduction, thin sample layering (0.3-1 mm) and precise fractionation after electrophoresis. A bottom circular palladium anode (nongassing) was separated hydrodynamically but not electrically from the density gradient by a cationpermeable membrane. A top circular platinum cathode caused negatively charged particles to migrate upwards (levitation). Thin sample layering permitted short separation times (30-60 min) at only 3 V/cm (10 mA). As for proteins, glycoforms of α1-antitrypsin were separated as well as isoenzymes of β-hexoseaminidase. Furthermore, separation of transferrin (Tf) from the putative Tf-receptor complex was effectuated. The device was equally suitable for the separation of Megadalton proteins (mucins). Artificial mixtures of intact erythrocytes (rat, rabbit, human) were separated with high resolution. About 107 cells (of 100 μm3 cell volume) could be loaded onto the device. Crude microsomes from the human melanoma cell line Mel JuSo were separated after brief trypsin treatment within 38 min at 10 mA. Ratios of the migration velocities of the constituent organelles were: late endosomes (LE) : lysosomes (L) : Golgi (G) : early endosomes (EE) = 1 : 0.94 : 0.77 : 0.55 and under slightly different conditions LE : L : G : endoplasmatic reticulum (ER) : plasma membrane (PM) = 1 : 0.87 : 0.64 : 0.58 : 0.49.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 173-178 
    ISSN: 0173-0835
    Schlagwort(e): Separation of cellular organelles ; Endosomes ; Lysosomes ; Endoplasmic reticulum ; Plasma membrane ; Density gradient electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: A density gradient electrophoresis apparatus made of Perspex was constructed, with a separation column (7 × 2.2 cm) containing a 0-5% linear Ficoll gradient. The useful separation path is 6 cm. A specially designed gradient mixer is described which fits over the application cone. This cone permits precise gradient and sample introduction as well as undisturbed fractionation after electrophoresis. A bottom circular palladium cathode is separated hydrodynamically but not electrically from the density gradient by a cellophane membrane, merely secured by an O-ring. The top circular platium anode allows for upward electrophoresis (80-100 min at 10 mA). The markedly higher resolution of subcellular organelles was compared with separations obtained earlier with a small, but much more difficult to fabricate, prototype. Moreover, ease of manipulation was greatly improved. A wide separation distance was obtained between plasma membrane, endoplasmatic reticulum as well as between two populations of lysosomes. Even early, middle, and late endosomes could be separated with high resolution. Soluble isoenzymes could be separated as well and were far away from the vesicle-enclosed enzymes.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 18 (1997), S. 2509-2515 
    ISSN: 0173-0835
    Schlagwort(e): Density gradients electrophoresis ; Proteins ; Organelles ; Transferrin receptor ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Following a concept developed by Bier et al. (Electrophoresis 1993, 14, 1011-1018), binary mixtures of amphoteric buffers with low conductivity and a good buffering capacity permit rapid rate zonal separation of proteins on a density gradient electrophoresis apparatus (7 cm, Ø 2.2 cm). At pH 8.66 and 250 V, β-lactoglobulin (Mr 36 600) was separated into the A and B isoforms within 44 min; human transferrin (Mr 76 000-81 000) was separated into its sialylated glycoforms and carbonic anhydrase (Mr 30 000) separated into its isoenzymes. From these results we arrive at the term high-performance density gradient electrophoresis. Compartments belonging to the endosomal system were separated by density gradient electrophoresis. Early endosomes, recycling vesicles, intermediate endosomes, late endosomes and lysomes became well-separated after 80 min at 10 mA using [125I]transferrin and horseradish peroxidase as reporter molecules in pulse-chase regimes. Mixtures of Bier buffers and standard electrophoresis media permitted very short separation times (19 min at 10 mA) for the endosomal compartments. Concommittantly, endoplasmic reticulum and proteasomes were well resolved.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 0173-0835
    Schlagwort(e): Buffer electrofocusing ; Density gradient electrophoresis ; Separation of proteins ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: A density gradient electrophoresis apparatus made of Perspex (7 cm, Ø 2.2 cm) with a circular platinum anode and a palladium cathode was used for the separation of proteins in free liquid. Following a concept developed by M. Bier et al. (Electrophoresis 1993, 14, 1011-1018), mixtures of two suitable amphoteric buffers I and II provide for media with a fixed and electrophoretically stable pH or were used for the generation of preformed (electrophoretically stable) pH gradients covering about 1 pH unit. Amphoters I and II are considered suitable if there is overlap between (pK1,1-1-2) and the pK2,II+1+2) region. 3-(N-Morpholino)propanesulfonic acid (MOPS) and γ-amino-n-butyric acid (GABA) were used as an example. Two approaches were followed: (i) rate-zonal separation of test proteins in a pH window, formed by a fixed ratio of MOPS/GABA. (ii) Isoelectric focusing in a shallow preformed pH gradient, made up of inverse reciprocal linear gradients of MOPS and GABA. At isopH, test proteins (bovine serum albumin, cytochrome c, ferritin, hemoglobin, lactoglobulin, myoglobin, and transferrin) were rate-zonally separated within a short time. Even the separation of the A and B forms of lactoglobulin was feasible at isopH. The glycoforms of transferrin were separated and enriched on a pH 5.2-6.1 pH gradient, indicating that pH differences of about 0.01 still permit resolution. Contrary to the ill-defined Ampholines, the cost of these well-defined amphoters is lowPresented at the “Elektrophorese Forum “96” meeting of the German Electrophoresis Society, held at the Technical University Munich, October 23-25, 1996.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    ISSN: 0173-0835
    Schlagwort(e): Density gradient electrophoresis ; Endosomes ; Clathrin ; Proteasomes ; Proteins ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: A density gradient electrophoresis (DGE) apparatus (2.2 Ø, 14 cm) was constructed for the rapid separation of milligram quantities of proteins. By using binary buffers according to Bier (Electrophoresis 1993, 14, 1011-1018) proteins were rate-zonally separated in less than 60 min. Acidic proteins were separated in a pH 8.6, 56 μS/cm buffer, and basic proteins in a pH 5.4, 76 μS/cm buffer. Thus the A (pI 5.15) and B (pI 5.30) forms of β-lactoglobulin as well as the sialylated glycoforms of apotransferrin were well separated at pH 8.6. The isoforms of myoglobin (pI 6.9 and 7.35, respectively), RNAse A (pI 9.45) and cytochrome c (pI 10.0) and lysozyme (pI 11) were separated at pH 5.4 within 80 min. On a 7 cm DGE column, subcellular organelles derived from HeLa cells were separated in standard electrophoresis buffer (655 μS/cm) for 90 min at 10 mA. Using a new low conductivity buffer (193 μS/cm) 20 min was sufficient to separate late endosomes, lysosomes, endoplasmic reticulum, early endosomes, plasma membrane, clathrin-coated pits, proteasomes, and clathrincoated vesicles within a single run directly from a postnuclear supernatant.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 13 (1992), S. 662-664 
    ISSN: 0173-0835
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: A solid aluminum block, connected with a warm and cold thermostated waterbath, provided for a linear transversal temperature gradient (TG) during polyacrylamide gel electrophoresis (PAGE). Noncovalently bound heavy chain dimers as well as heavy-light chain dimers, derived from human monoclonal IgG, could be melted into monomers using a 40-75°C TG under conditions of sodium dodecylsulfate-PAGE. Using native PAGE, majorhistocompatibility complex (MHC) class I molecules, preloaded with the iodinated peptide FAPGNYPAL could be melted in a 4-40°C TG to release the peptide. The method is in general applicable to thermal stability analysis of noncovalently bound hetero-oligomers if the product after melting possess different electrophoretic mobilities.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    ISSN: 0173-0835
    Schlagwort(e): Density gradient electrophoresis ; Endosomes ; Proteins ; Organelles ; Transferrin ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: We have developed a density gradient electrophoresis device (DGE) and used it for the preparative separation of various endocytic organelles that are hard to separate by other means. Our separation by DGE of late endosomal vesicles, recycling vesicles, early endosomes and plasma membranes is unmatched. Using the same DGE device, we performed preparative high-resolution rate zonal separation of proteins using amphoteric buffers as originally described by Bier (Electrophoresis 1993, 14, 1011-1018). Isoforms of bovine β-lactoglobulin, human apo-transferrin, and bovine erythrocyte carbonic anhydrase that have isoelectric points within 0.8 pH units were readily separated even in the absence of nonionic detergents. The DGE apparatus is inexpensive and has unique separation abilities for vesicles and proteins.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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