摘要:

AbstractUsing an original protocol with a rotating gel electrophoresis apparatus, it is shown that duplex DNA undergoing crossed‐field electrophoresis in agarose gets trapped in the gel when the field is increased above a threshold value which decreases with the chain length and depends on the angle between the fields in a non‐monotonous manner. This trapping is irreversible,i.e.once trapped at a high field strength, chains are unable to resume their motion when the field is returned to a lower value at which they moved prior to trapping. A model of trapping by “tight knots” is proposed. It predicts a trapping threshold proportional to the inverse square of the electric field, in qualitative agreement with the data. The implications of our results for the separation of large DNA molecules are di

ISSN:0173-0835    

DOI:10.1002/elps.1150130102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractSimple repetitive DNA sequences have been regarded as mere “junk” present in all eukaryotic genomes. In fact, mixed simple repeat (gt)n(ga)msequences are present in major histocompatibility complexMHC‐DRBgenes for long evolutionary times, including such distant animals as artiodactyla and man. We describe herein an unsophisticated method which reveals that at least certain simple repetitive (gt)n(ga)msequences bind nuclear proteins and show characteristics of a specific DNA‐protein interactionviagel reta

ISSN:0173-0835    

DOI:10.1002/elps.1150130103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractA novel concept is described for the statistical analysis of multilocus DNA fingerprints. Utilizing this method, it is shown by simulation that the application of multilocus DNA fingerprints to paternity testing is robust against deviations from idealistic assumptions made about underlying models and parameters. Partial homozygosity, allelism and linkage at the DNA loci involved, as well as variations in estimates of band‐sharing probabilities were studied for effects on the resulting paternity probabilities. None of the above‐mentioned phenomena appear to change these values to an extent relevant for decision making in paternity ca

ISSN:0173-0835    

DOI:10.1002/elps.1150130104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractCapillary electrophoretic separations of double‐stranded DNA fragments in the size range of 20–2200 base pairs were achieved in less than 20 min with the use of a Tris‐borate buffer containing hydroxyethylcellulose. Analyses were carried out in both uncoated and phenylmethyl‐coated capillaries of fused silica with internal diameters of 50 and 100 μm, respectively, and an effective column length of 50 cm. The addition of ethidium bromide resulted in an improved resolution of double‐stranded DNA fragments, thereby permitting even the separation of fragments differing only 1–2 base pairs in length. Moreover, resolution was found to be linearly proportional to the size of the cation used to adjust ionic strength Cs+>RB+>K+>Na+>Li+. However, the analysis times also increased with increasing cation size due to a decrease in electroosmotic flow. Elution order was verified by spiking restriction digests with slab gel electrophoretically purified components. Subsequently, the described system was applied to the detection and quantitation of an mRNA transcript of the androgen receptor, which had been amplified by polymerase chain reaction and purified by size‐exclusion chromatography to avoid peak broadening due to conductivity differences between sample and running buffer. Since the actual amount of DNA introduced into the capillary cannot be defined, molar ratio–peak area ratios of the polymerase chain reaction product to various restriction fragments of known concentration were used to determine the amount of amplified DNA. The coefficient of variation was as small as 3.4% and the results were in good agreement with a spectrop

ISSN:0173-0835    

DOI:10.1002/elps.1150130105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe upper limit of the size range of DNA amenable to separation in agarose solutions above their gelling temperature, using capillary zone electrophoresis apparatus, was increased to 12 kb. The plot of log(bp)vs.mobility derived from electrophoresis in 1.7% agarose solution is biphasic, exhibiting higher resolving power for DNA less than 1 kb in size than that of larger sizes. Resolving power for DNA larger than 1 kb increased when the agarose concentration was increased in the range of 1.0–2.6%. It was similar in solutions at 40°C of SeaPrep and SeaPlaque agaroses as well as in Acrylaide (trade names are those of the manufacturer). However, the resolving power of SeaPrep agarose at 25°C was inferior to that at 40°C. Concave plots of log(mobility)vs.concentration of the agarose solutions are those predicted under the assumption that the effective “equivalent radius” of the DNA molecule diminishes with increasing agarose concentration in the investigated concentration range up

ISSN:0173-0835    

DOI:10.1002/elps.1150130106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractCombining the effects of electrophoresis and electroendosmosis, flavonoids were separated in less than ten minutes in a fused silica capillary tube with a borate buffer adjusted to pH 10. An increase in the concentration of borate from 0.1 to 0.2Mresulted in longer migration times due to a decrease in electroosmotic flow, but also in improved selectivity and higher resolution of flavonoids. The calibration curve of rutin showed a detection limit of 0.02 mg/mL and linearity over its pharmaceutical concentration range. Using an internal standard of known concentration, the content of rutin in a methanolic extract ofSambuci floscould be determined with a coefficient of variation as small as 3.8% by the molar ratio – peak area ratio metho

ISSN:0173-0835    

DOI:10.1002/elps.1150130107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractErgot alkaloid enantiomer derivatives were resolved using capillary zone electrophoresis. The effect of cyclodextrins, added to the background electrolyte, on the migration time and the resolution was studied. Good separation for epimericergot alkaloid derivatives was also obtained using phosphate buffer at pH 2.5. Separation was improved by supplementing the background electrolyte with 30 mMof γ‐cyclodextrin. Good resolution of racemic ergot alkaloid derivatives in their enantiomers was achieved in a background electrolyte containing either β‐cyclodextrin or its derivative, or γ‐cycl

ISSN:0173-0835    

DOI:10.1002/elps.1150130108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractA computer program for high‐speed simulation and optimization of electrophoretic processes has been developed for carrier‐free systems of all kinds. The calculations are based on the one‐dimensional dynamic (transient‐state) model. The three‐dimensional geometry of the simulation space can be chosen deliberately. With a highly efficient transport algorithm instead of complicated integration schemes for the transport equations, the calculation time can be effectively spent on various important parameters such as ionic strength, temperature, Joule heat, activity coefficients and concentration changes due to membranes. The parameter set of any carrier free electrophoretic method (i.e., continuous‐flow electrophoresis, capillary isotachophoresis and high performance capillary zone electrophoresis) can be imported directly into the computer program by means of a graphic user interface. The program performs overnight‐simulation of any electrophoretic system containing up to

ISSN:0173-0835    

DOI:10.1002/elps.1150130109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe traveling‐wave‐induced linear transfer of dielectric particles like living cells and artificial objects of microscopic dimensions is analyzed. It is shown that the electrode geometries must correspond to particle sizes to allow an effective manipulation of particles immersed in weakly electrolytic solutions by high frequency traveling waves. The theoretical model elaborated in this paper is in good agreement with experimental results obtained in microfabricated chambers of linearly arranged electrodes. It explains the behavior of homogeneous cellulose spheres as well as that of membrane‐covered pine polls. The traveling‐wave‐driven electrodes are described by a superposition of time‐dependent point charges. Subsequently, each of these point charges has to be considered as polarizing the dielectric particle and interacting with the polarized particle. This results in forces which effectively translocate t

ISSN:0173-0835    

DOI:10.1002/elps.1150130110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractMulticompartment electrolyzers with isoelectric Immobiline membranes are used for large‐scale preparative protein purification. A series of isoelectric membranes, of defined pIvalues, is utilized for keeping any desired species isoelectric within each compartment of the electrolyzer. It is preferable to have electrode disks of the same surface area as the membranes for a proper performance of the instrument because electrolyte solutions of low conductivity are used. The use of Pt disks would be quite expensive; we therefore propose using Zr as a cathode and Ti/IrO2as an anode in the electrodic compartments. This pairing of electrodes seems to give the same performance as Pt wires. Also, conventional isoelectric focusing, as well as isoelectric focusing in immobilized pH gradients, both requiring a good contact area between gel and electrodes, would benefit by using flat laminae of these metals as electrode

ISSN:0173-0835    

DOI:10.1002/elps.1150130111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY