Changes in Molecular Weights and Molecular Weight Distributions of Differently Stranded Nucleic Acids after Sonication:  Gel Permeation Chromatography/Low Angle Laser Light Scattering Evaluation and Computer Simulation

Abstract

Changes of weight-average molecular weights (M w) and the molecular weight distributions in terms of weight fraction (g w) were evaluated in the course of sonication for three nucleic acids in different conformations by the gel permeation chromatography/low angle laser light scattering (GPC/LALLS) method. High M w samples used were single-stranded poly(uridylic acid), (U) n , double-stranded DNA, and triple-stranded poly(adenylic acid)·2poly(inosinic acid), (A) n ·2(I) n , in 0.2−0.1 M NaCl at 0 °C. The experimental g w vs M curves were computer-simulated for different chain-scission mechanisms: (1) random, (2) midpoint, (3) Gaussian, (4) classical partially random, and (5) newly proposed partially random scission models. In comparison with the GPC/LALLS data, the middle portion of each single- or multiple-stranded chain was sheared randomly, whereas the adjacent end portions of the chain resisted sonic scission. The M w value of each intact end portion was 1.0 × 105 for (U) n , 1.5 × 105 for DNA, and 1.7 × 105 for (A) n ·2(I) n , corresponding to the lowest possible M w for the sonicated but unfractionated nucleic acid samples under the present conditions.

Statistical Mechanics and Kinetics of Amyloid Fibrillation

“…In literature, several assumptions have been proposed, including the random scission, the central scission, and the Gaussian scission [106,107] and modified partially random scission [108] etc. The latter two got supports from fiberlike PI264-b-PFS48 micelles under sonication [109], thermodynamically induced shear degradation of polystyrene in semiconcentrated solutions [107], singlestranded random-coiled poly-(uridylic acid), double-stranded helical DNA, and triple-stranded helical poly-(adenylic acid)·2poly(inosinic acid) [108]. Hill suggested a formula in log form for polymer fragmentation and annealing based on statistical mechanics [110].…”

Molecular weight distribution in low-density polyethylene polymerization; impact of scission mechanisms in the case of a tubular reactor

“…There have been various suggestions of correlating the scission phenomena for mechanical scission with mathematical expressions (Casale and Porter, 1978;Tanigawa et al, 1996;Toyal and Khan, 2000). Their scission models suggested scission probability as a function of fragment length and chain length.…”

Rheological Characterization of Computationally Synthesized Reactor Populations of Hyperbranched Macromolecules: Bivariate Seniority‐Priority Distribution of ldPE

“…Find terminal branches: Figure A1). Similarly, starting with vertex 1 and vertex 5 yields the sequences {e 12 e 23 e 24 e 45 } and {e 54 e 42 e 21 e 23 } with sequence numbers {2 3 3 4} and {2 3 4 4}, respectively. Collecting the sequence numbers per edge yields the vectors n s (e ij ) shown in Figure A1 and then taking maxima and minima according to step 6 of the algorithm yields the seniority distribution d S .…”