The effect of formaldehyde on ribosomal conformation was investigated spectrophotometrically and viscometrically. Thermal denaturation of ribosomes dissolved in 1 mM sodium acetate (pH 7.4) in the presence of formaldehyde results in: 1. (1) A decrease in the melting temperature (Tm), from 63° in the absence of formaldehyde, down to 51° in the presence of 9.4 % reagent. 2. (2) Irreversibility of the hyperchromicity upon cooling. 3. (3) Shift of λmax from 257 to 262 nm. Viscometric measurements in the presence of formaldehyde at different temperatures revealed no changes in specific viscosity (ηsp), due to fixation. Parallel experiments with ribosomes and ribosomal RNA where ηsp was measured at different formaldehyde concentrations, show that the presence of ribosomal proteins attached to the rRNA, increases the fixation markedly compared with free rRNA. The ηsp values of rRNA at high temperatures decrease gradually with increasing formaldehyde concentration. Due to the fixation, the high ηsp value of rRNA obtained at high temperature is retained on cooling.
|Number of pages||7|
|Journal||BBA Section Nucleic Acids And Protein Synthesis|
|State||Published - 14 Dec 1970|
ASJC Scopus subject areas
- Medicine (all)