The effect of reaction with formaldehyde on the sedimentation rates of ribonucleic acids

Abstract

It has been reported that the RNA of several bacteriophages and that of the larger ribosomal sub-units of mammalian cells sediment faster in the presence of 0.1m-sodium chloride than is expected from their estimated molecular weights. The effect of blocking the hydrogen-bonding amino groups of these and other types of RNA was studied. The RNA of phage R17 no longer sedimented anomalously fast after treatment with formaldehyde. In contrast, the larger ribosomal RNA of HeLa cells appeared more aberrant than before, sedimenting faster than tobacco-mosaic-virus RNA (mol.wt. 2x10(6)) in the presence of formaldehyde. The rapidly labelled nuclear 45s RNA of HeLa cells still sedimented faster than the larger ribosomal RNA after reaction with formaldehyde, showing no evidence of disaggregation. It is suggested that both the large ribosomal RNA and the 45s RNA of HeLa cells may have a non-linear structure.

A Model for Foot-and-Mouth Disease Virus

“…The molecular weight of the 12s sub-unit is thus considerably less than the values of 420 and 41o × IO 3 given by to be 2-0 to 3"r x ~o 6 (Strohmaier & Mussgay, 1959;Wild & Brown, 197o;Liebermann & Schulze, I971). Using the method described by Fenwick (1968) (Tannock,Gibbs & Cooper,197o) it seemed reasonable to use a value of 2-6 x lO 6 for the molecular weight of foot-and-mouth disease virus R N A in our calculations. Since the R N A comprises 3I % of the virus particle (Bachrach,Trautman & Breese,I964), the molecular weight of the virus is 2-6 x lO 6 x IOO/3I = 8"4 x I@, of which the protein will contribute 5"8 x io n. The value for the molecular weight of the virus is similar to those given by Scraba, Kay & Colter (I967) and Burness & Clothier (I97O) for Mengo and encephalomyocarditis viruses respectively but is considerably greater than that given by Liebermann & Schulze (197I) for foot-and-mouth disease virus.…”

Specific binding of ribonucleic acid by antiadenosine antibodies

“…Uridine did not inhibit the reaction, thus indicating further its lack of specificity. It is also possible that the RNA was degraded by the formaldehyde denaturation conditions used (Boedtker, 1968;Fenwick, 1968). The RNA was ClgCCOOH precipitable but limited digestion could have occurred.…”

The Characterization of a Set of Amber Mutants of Bacteriophage T5

“…Gradients (4.5 ml) of 15 to 30~o sucrose in 0.05 M-Tris-HCI buffer pH 7-5 were prepared by the method of Fenwick (1968). They were loaded with 0.5 ml of mutant product lysate, centrifuged at 18 000 r.p.m, for 25 rain at 20 °C in a Beckman SW50.1 rotor and analysed by upward displacement in an Isco ultraviolet fractionator.…”