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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 1 (1980), S. 102-106 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A device for the measurement of segmental voltages along electrofocusing gels made of polyacrylamide has been designed and tested successfully. It allows for continuous monitoring of the changing voltage gradients which occur during electrofocusing. By means of 11 equidistant embedded platinum probes, the voltage drop at any one segment or sequential array of segments can be determined at any time without disturbing the ongoing electrofcusing. The wires are sealed into the wall of a 6 mm diameter (ID) Pyrex gel tube at 1.0 cm intervals. Measurements on a gel containing 2% Ampholine (pH-range 3.5-10) showed that the voltage gradient changes during electrofocusing. Starting with a uniform voltage drop of 10 ± 2%cm across a 10 cm gel, two transient peaks of high potential (comprising at 15 min 17% and 25% of the applied voltage) move progressively from the gel periphery toward its center. They coalesce into a broad single peak centered at 0.4 of the distance from the anodic gel terminus within 1.5 h. This major single peak remained stationary, changing slightly in magnitude during the next 18 h of electrofocusing. At this final stage, the voltage peak occurred at pH 6.3 and approximately 25% of the applied voltage was across this segment of gel.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 1 (1980), S. 107-113 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Conductivity gaps in electrofocusing gels were measured as a function of the duration of isoelectric focusing, using a device for the determination of segmental voltage along the gel length (Jackiw, B. A., et al., Electrophoresis 1980, 1, 102-106 Transient and permanent conductance gaps were found on electrofocusing with both commercial and home-made carrier ampholytes of a variety of pH-ranges and chemical compositions. All pH gradients investigated exhibited conductance gaps. The dynamics of conductance gap formation and the relative magnitude of voltage maxima were compared in electrofocusing gels made with the various types of carrier ampholytes, With ampholyte-ampholyte mixtures, and with ampholyte-amino acid mixtures.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A natural pH gradient can be formed on polyacrylamide gel using either two (glutamic acid and lysine only) or three (glutamic acid, histidine and lysine) aminoacids as the sole carrier ampholyte species. In the two component system, glutamic acid and lysine focus as single peaks adjacent (anodically and cathodically, respectively) to the steep, linear center of the step-function pH gradient. Histidine, in the three component system, focuses at the center of the pH gradient and separates the other two aminoacids. Each aminoacid electrofocuses at its pI. Hemoglobin electrofocuses as a sharp band in both systems and, in the two component system, remains focused at its pI for 200 h. A major conductance gap forms at the gel center in both systems with progressing time of electrofocusing; a minor and transient conductance gap develops in the glass tube just above the gel.
    Additional Material: 4 Ill.
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  • 4
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A zwitterionic methacrylamide derivative, (3-sulfopropyl)dimethy1(3-methacrylamidopropyl) ammonium inner salt (MAPS), was synthesized and then copolymerized with N,N′-methylenebisacrylamide (Bis) to make gels carrying covalently bound sulfobetaine groups. Gels were also prepared with the addition of (3-sulfopropyl)trimethyl ammonium inner salt (TMAPS) to Bis-crosslinked polyacrylamide prior to polymerization. The properties of these gels in gel electrophoresis and electrofocusing were tested and compared with those of Bis-crosslinked polyacrylamide.In MAPS gels the absolute migration velocities of proteins and dyes at either polarity of migration were decreased. Anionic species were much more strongly retarded than cationic species. Ferguson plots (based on protein mobilities relative to dye in a continuous buffer) of catalase at pH 4 obtained on MAPS gels had a similar slope but lower y-intercept compared with those on equivalent polyacrylamide gels, indicating that the available (effective) net charge on the protein was decreased because it interacts with the zwitterionic charge on the gel. Similarly, the addition of TMAPS to polyacrylamide decreased the relative catalase mobility at non-restrictive gel concentrations. However, at gel concentrations above 4 %T, relative mobilities were increased, presumably because the effective pore size of the gel was increased through inhibition of polymerization by the zwitterionic compound.MAPS gels did not exhibit electroendosmosis by the criterion of cyanocobalamin displacement. Resolution between peptides in MAPS gels, and between proteins in ternary copolymer gels made of MAPS, Bis and polyacrylamide, was similar to that on polyacrylamide. Bands of catalase appeared sharpened in MAPS gels. pH Gradients form, decay and exhibit conductance gaps in MAPS electrofocusing gels and in polyacrylamide gels in presence of 0.25-1.5 M TMAPS, in a manner which was qualitatively indistinguishable from polyacrylamide.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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