scholarly journals A spectrophotometric study of the secondary structure of ribonucleic acid isolated from the smaller and larger ribosomal subparticles of rabbit reticulocytes

1970 ◽  
Vol 117 (1) ◽  
pp. 101-118 ◽  
Author(s):  
R. A. Cox

The spectrum of RNA from the smaller and larger subparticles of rabbit reticulocyte ribosomes was studied as a function of pH, ionic strength, urea concentration and temperature. It was inferred that both RNA species form short double-helical segments of not more than about 10 base-pairs in length. Not more than about 70% of the base residues may be located in double-helical segments. RNA from the larger subparticle is richer in guanine and cytosine residues and its secondary structure is the more stable. These conclusions are based on the use of double-helical RNA from virus-like particles and of unfractionated Escherichia coli tRNA as model systems.

1976 ◽  
Vol 160 (3) ◽  
pp. 505-519 ◽  
Author(s):  
R A Cox ◽  
W Hirst

Mg2+ was shown to affect the conformation of rRNA over the range of 0.03-1.2M-KCl. The species studies were Escherichia coli S-rRNA and L-rRNA (the RNA moieties of the smaller and larger subribosomal particles respectively) and rabbits S-rRNA and L-rRNA. 2. The addition of Mg2+ to rRNA in reconstitution buffer (0.35M-KCl0.01M-Tris/HCl, pH7.2) at 20° C let to an increase in bihelical secondary structure through the formation of additional (mainly A-U) base-pairs (e.g. an additional approx. 58 A-U base-pairs per molecule of E. coli S-rRNA as judged by u.v. difference spectrophotometry…


1973 ◽  
Vol 135 (2) ◽  
pp. 349-351 ◽  
Author(s):  
A. A. Hadjiolov ◽  
R. A. Cox

The spectrophotometric analysis of 45S precursor rRNA shows that it contains more G and C residues than does mature 28S or 18S rRNA. The helical content and the length of double-helical segments in 45S and 28S rRNA are similar.


1968 ◽  
Vol 108 (4) ◽  
pp. 599-610 ◽  
Author(s):  
R A Cox ◽  
K Kanagalingam

1. The thermal denaturation of DNA from rat liver was studied spectrophotometrically. In sodium phosphate buffers denaturation led to a single-stranded form having, at 25°, about 25% of the hypochromism of the intact double helix. 2. The hypochromism of the denatured form was the same in 1mm- as in 10mm-sodium phosphate buffer and was scarcely affected by reaction with formaldehyde. The hypochromism was decreased by about 40% in the presence of 8m-urea. 3. The hypochromism of denatured DNA at low ionic strengths was about the same as that of fragments of reticulocyte ribosomal RNA that were too short to form double-helical secondary structure and about the same as that of RNA after reaction with formaldehyde. 4. The spectrum of DNA was slightly affected by the presence of 8m-urea or 4m-guanidinium chloride. The differences in the spectrum of the native and denatured forms of DNA in 0·1m-sodium phosphate buffer, in 8m-urea–10mm-sodium phosphate buffer and in 4m-guanidinium chloride–10mm-sodium phosphate buffer, pH7·6, were similar but not identical. 5. Denatured rat liver DNA appears to have no double-helical character at 25° in 10mm-sodium phosphate buffer, pH7·6; increasing the buffer concentration to 0·1m leads to a more compact form in which about 40% of the residues form base pairs.


1970 ◽  
Vol 245 (6) ◽  
pp. 1401-1406 ◽  
Author(s):  
H. Hayashi ◽  
J.R. Knowles ◽  
Jon R. Katze ◽  
J. Lapointe ◽  
Dieter Söll

1970 ◽  
Vol 245 (10) ◽  
pp. 2679-2692
Author(s):  
David A. Sirbasku ◽  
John M. Buchanan

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