STUDY OF CONFORMATIONAL AND DYNAMIC CHANGES IN PHAGE-LAMBDA DNA BY DYNAMIC LIGHT-SCATTERING

Conformational and dynamic changes in the macromolecules of phage lamb da DNA were studied by dynamic light scattering (DLS). The experimenta l data were processed using a regularization procedure. Under certain conditions the persistence length of B-DNA was shown to decrease to si milar to 12 nm. Analysis of internal motions in the linear DNA reveale d a deviation of the experimental angular dependence of the first cumu lant <(Gamma)over bar> from the theoretically predicted behavior in th e Rouse-Zimm model with exact account of hydrodynamic interaction at q Rg >> 1 (R(g) is gyration radius and q is momentum vector). The deviat ion to higher frequencies was observed only with B-DNA. For A-DNA the experimental behavior of <(Gamma)over bar> coincided with the Rouse-Zi mm model predictions.