Quasielastic light scattering by biopolymers. Center-of-mass motion of DNA in the presence of a sinusoidal electric field

✍ Scribed by Kenneth S. Schmitz

• Publisher: Elsevier Science
• Year: 1979
• Tongue: English
• Weight: 598 KB
• Volume: 63
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(79)87013-x

✦ Synopsis

Quasielastic light scattering is now a ~rcll-established technique for rapid determination of diffusion coefticients from the spectral density of Rayleigh scattered tight. Application of a constant electric field in the course of a quasiehstic light scattering experiment. a technique termed electrophoretic light scattering (ELS), results in a series of peaks that are Doppler shifted by an amount proportioual to the superimposed instantaneous velocity of the molecules_ Electrophorettc mobrhtres, diffusion coefficients, and relative concentrarions of each component in a polydispersed system cm be determined from a single ELS e.\perirnent. A theory for polymer dynamics in the presence of an applied sinusoidal field has also bcei proposed. The present commuuication presents data in xvhich the center-of-mass motion of DNA is studied in the presence of a lowfrequency sinusoidal field. It is shown that: (1) at very low frequencies t!te po\rer spectrum is composed af seven1 peaks Doppler shiftsd by an amount proportional to the driving frequency w (i.e. fundamental and harmonic overtones); (2) the pe& amplitude of the fundamental frequency shift is proportioml to l/w iu accordance rvith the theory_ The advantage of using a sinusoidal applied field instead of a pulsed square-wave is discussed_