Dégradation de L'Acide Ribonucléique Microsomal par les Ultrasons

Abstract

SUMMARYThe action of sonic radiations (20 Kc) on RNA solutions has been studied in relation with structural characterizations. Ribosomal RNA from calf thymus was used; it had two components with molecular weights 1.3.106 and 0.5.106. The content of helical parts was estimated from hypochromic effect as 56%.Several sonicates were prepared using times of sonication from 2 minutes to 6 hours. Their intrinsic viscosities and sedimentation constants were determined. The minimum molecular weight which could be obtained was 60,000. Optical rotation and ultraviolet absorbancy of native and sonicated RNA samples were the same, indicating that the secondary structure was not modified by sonication. The influence of pH and dilution on absorbancy was also the same for all samples.The variation of viscosity with ionic strength was used as a means for estimating the flexibility of the molecules. These determinations showed that the sonicated RNA has a smaller degree of flexibility than the undegraded sample.It was concluded that by sonication the polynucleotidic chains of RNA molecules are split mostly in the disordered regions.