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Full-Text Articles in Physical Sciences and Mathematics
Structural Changes And Enhancements In Dnase I Footprinting Experiments?, Jerry Goodisman, James C. Dabrowiak
Structural Changes And Enhancements In Dnase I Footprinting Experiments?, Jerry Goodisman, James C. Dabrowiak
Chemistry - All Scholarship
In footprinting experiments, an increase in DNA cleavage with addition of ligand to a system may be due to a ligand-induced structural change. Ligand binding also enhances cleavage by displacing the cleavage agent from ligand-binding sites, thus increasing its concentration elsewhere. The theory and characteristics of this mass-action enhancement are given, and it is shown how it may be recognized. Results of DNase I footprinting of small oligomers, with actinomycin D as ligand, are analyzed to reveal which enhancements are due to mass action, and which can reasonably be ascribed to structural changes. Patterns in the footprinting plots from our …
Site-Specific Binding Constants For Actinomycin D On Dna Determined From Footprinting Studies, Jerry Goodisman, Robert Rehfuss, Brian Ward, James C. Dabrowiak
Site-Specific Binding Constants For Actinomycin D On Dna Determined From Footprinting Studies, Jerry Goodisman, Robert Rehfuss, Brian Ward, James C. Dabrowiak
Chemistry - All Scholarship
We report site-specific binding constants for the intercalating anticancer drug actinomycin D (Act-D), binding to a 139-base-pair restriction fragment from pBR 322 DNA. The binding constants are derived from analysis of footprinting experiments, in which the radiolabeled 139-mer is cleaved using DNase I, the cleavage products undergo gel electrophoresis, and, from the gel autoradiogram, spot intensities, proportional to amounts of cleaved fragments, are measured. A bound drug prevents DNase I from cleaving at -7 bonds, leading to decreased amounts of corresponding fragments. With the radiolabel on the 3’ end of the noncoding strand (A-label), we measured relative amounts of 54 …
Surface Tension Of A Charged And Polarized System, Jerry Goodisman
Surface Tension Of A Charged And Polarized System, Jerry Goodisman
Chemistry - All Scholarship
Usually, the formula for the surface tension of a planar charged and polarized interface is obtained from that for a system involving only short-range forces, y = - dz [p - px(z)] by replacing the tangential pressure p , by p , + E2/8u. Problems with this include (a) p, is no longer explicitly defined, (b) the electrostatic stress term E2/8 pi is not correct in general but only if polarization is proportional to density of polarizable species, (c) the derivation of the formula in terms of p and p, involves calculating the work to expand a volume containing the …