Some physical properties of bacteriophage R17 and its ribonucleic acid

摘要: The molecular weight of bacteriophage R17 in 0·15 M -NaCl + 0·015 -sodium citrate ( S 20,w = 79 to 80 s) was measured by light scattering and found be 3·6 ± 0·3 million. (by scattering) RNA prepared from phage at salt concentrations between 0·1 0·01 -Na , 1·1 million, independent the counterion concentration. Evidence that one million represents a single polynucleotide chain not an aggregate subunits obtained measurements sedimentation coefficient as function time heating 70 90°C. Brief exposure 70°C had little effect on even though helical regions were melted when exposed this temperature; 90°C slow decrease is consistent with random degradation, first-order rate constant for bond scission being 2·9 × 10 −7 sec −1 . solution conformation more compact than other ribonucleic acids studied date. However, there no evidence tighter packing reflects unusual secondary structure. Comparison relative absorbance-temperature profiles reactivity formaldehyde tobacco mosaic virus E. coli ribosomal reveal only slight differences; these are guanine-cytosine content three different RNA's.