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  • Ampholytes  (3)
  • DNA electrophoresis  (3)
  • 1
    ISSN: 0173-0835
    Schlagwort(e): Polyacrylamide ; Agarose ; Mixed matrices ; DNA electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: The average pore size value of gels containing polyacrylamide, covalently linked to agarose, was found to be 30% higher than the value of a regular N,N′-methylenebisacrylamide (Bis) cross-linked gel of the same %T. By increasing the agarose concentration (10% of the total amount of polyacrylamide), gels containing low amounts of acrylamide (1.5-2%) are reproducibly obtained; their pore sizes are 130% larger than the pore sizes of a 4%T, 3.3%C polyacrylamide gel. In general, mixed-bed matrices were found to be more elastic and mechanically stronger than classical polyacrylamide gels since an agarose-induced gelation process takes place during their polymerization.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 1596-1600 
    ISSN: 0173-0835
    Schlagwort(e): Isoelectric focusing ; Steady state ; Ampholytes ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: The equation of balance between electrophoretic and diffusional mass flows in the steady state of isoelectric focusing is analyzed. To create the pH gradient, a model system composed of only one Immobiline is used. The solution is found for the case of a small sample concentration, but without assumptions about linear “focusing force” and constant (linear) conductivity profiles. The effect of sample concentration on the final concentration profile is also evaluated. At high sample concentrations, it is demonstrated that the steady-state distribution is essentially non-Gaussian and results in a considerably lower concentration maximum as compared with low sample levels.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2269-2272 
    ISSN: 0173-0835
    Schlagwort(e): Natural pH gradients ; pH monotony ; Ampholytes ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: The problem of stationary electrolysis of a single-component ampholyte solution is analyzed. The effect of nonconstant relative mobility is taken into account. It is demonstrated that an incorrect dissociation model (i.e., expressing the resulting ampholyte flux by the arithmetic sum of the fluxes for “cationic” and “anionic” species) may lead to the violation of the so-called “law of pH monotony”.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 4
    ISSN: 0173-0835
    Schlagwort(e): N-Substituted acrylamides ; DNA electrophoresis ; Capillary electrophoresis ; Thalassemias ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: The behavior of different sieving polymers for unambiguous determination of point mutations in genomic DNA, based on electrophoresis in thin capillaries, is evaluated. High melters from thalassemia patients are separated by exploiting the principle of denaturing gradient gel electrophoresis, in fact, of its variant utilizing temperature gradients (TGGE), along the migration path, encompassing the melting points of both homo- and heteroduplex, polymerase chain reaction (PCR)-amplified DNA fragments. Unlike TGGE, where the temperature gradient exists along the separation space, the denaturing temperature gradient in the fused-silica capillaries is time-programmed, so as to reach the Tm's of all species under analysis prior to electrophoretic transport past the detector window. The DNA fragments are injected in a capillary maintained (by combined chemical and thermal means) just below the expected Tm values. The ΔT applied is rather minute (1-1.5°C) and the temperature gradient quite shallow (e.g., 0.05°C/min). The denaturing thermal gradient is generated internally, via Joule heat produced by voltage ramps. This method is applied to the analysis of the most common point mutations in thalassemias, characterized by being high melters (in the temperature range of 60-62°C) in presence of 6 M urea. Point mutants are fully resolved into a spectrum of four bands only when poly(N-acryloylaminopropanol) and hydroxyethylcellulose are used. However, the former offers the best separation capability at such high temperatures.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    ISSN: 0173-0835
    Schlagwort(e): N-Substituted acrylamides ; DNA electrophoresis ; Capillary electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: The behavior of N-substituted poly(acrylamides) and of cellulose in the separation of double-stranded DNA by capillary zone electrophoresis (CZE) is evaluated. Contrary to previously held belief, which attributed best separations in poly(acrylamides) to small DNA fragments (typically in the 50-1000 bp size range) and in celluloses to large DNA fragments, we show that also celluloses can achieve fine sieving of short DNA sizes provided they are used at much higher concentrations than previously reported. For example, in the case of hydroxyethylcellulose (HEC), typically used at 0.2-0.8% concentrations, levels of 3% produce excellent patterns, at 25°C, in the 50-600 bp size range. If separations are conducted at 60°C, sieving is lost in most liquid polymers. However, if the concentration of HEC is raised to 6%, and that of hydroxypropylmethylcellulose (HPMC) above 1%, sieving is fully restored. Also, N-substituted acrylamido derivatives, notably N-acryloylaminoethoxyethanol (AAEE) and N-acryloylaminopropanol (AAP) offer excellent performance at both 25° and 60°C, whereas plain poly(acrylamide) irreversibly collapses at high temperatures, possibly due to intrinsic instability of the amido bond under such harsh conditions. Among all the polymers investigated, an 8% solution of poly(AAP) offers the best performance and highest theoretical plates in the 25°-60°C interval. Separations at high temperatures are necessary when dealing with detection of point mutations in temperature-programmed CZE and are preferred in DNA sequencing. Two additional advantages are evident when running DNA separations at 60°C: a marked reduction of analysis times and a linearization of the transit times of the larger (434-587 bp) DNA fragments, in all polymers tested.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    ISSN: 0173-0835
    Schlagwort(e): Ampholytes ; Buffering power ; ΔpK values ; pH gradients ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: For calculating the buffer capacity of ampholytes an application of the stepwise and parallel dissociation models is considered. It is demonstrated that the scheme with stepwise dissociation possesses a “nonadditive” sum, i.e., the resulting buffer capacity of the system exceeds the sum of the separate contributions of the two ionogenic groups. On the other hand, the scheme of parallel dissociation is free from this disadvantage, and thus does not impose any restriction on the ΔpK parameter.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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