Association of Ribonuclease I with Ribosomes and Their Subunits

RNase I of Salmonella typhimurium has been purified to a homogeneous state. It has a molecular weight of 2 x 104. Association of RNase I with the 30 S subunits of ribosomes has been investigated by using an inhibition assay. 70 S ribosomes and 30 S subunits, but not the 50 S subunits, inhibit the hy...

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Bibliographic Details
Published in:The Journal of biological chemistry 1972-11, Vol.247 (21), p.6795-6801
Main Authors: Datta, Alok K., Burma, Debi P.
Format: Article
Language:English
Subjects:
Adenine Nucleotides
Ammonium Sulfate
Chemical Precipitation
Chlorides - pharmacology
Chromatography, DEAE-Cellulose
Chromatography, Gel
Chromatography, Ion Exchange
Escherichia coli - cytology
Lithium - pharmacology
Macromolecular Substances
Magnesium - pharmacology
Molecular Weight
Polynucleotides
Potassium Chloride - pharmacology
Protein Binding
Proteins
Ribonucleases - antagonists & inhibitors
Ribonucleases - isolation & purification
Ribonucleases - metabolism
Ribosomes - drug effects
Ribosomes - metabolism
RNA, Ribosomal
RNA, Transfer
Salmonella typhimurium - enzymology
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Summary:RNase I of Salmonella typhimurium has been purified to a homogeneous state. It has a molecular weight of 2 x 104. Association of RNase I with the 30 S subunits of ribosomes has been investigated by using an inhibition assay. 70 S ribosomes and 30 S subunits, but not the 50 S subunits, inhibit the hydrolysis of polyribonucleotides (only poly adenylic acid was used in the present investigation) by RNase I. This inhibition is Mg++-dependent. Each 30 S subunit appears to bind approximately 3 molecules of enzyme. The three-dimensional configuration of the ribosomes is essential for the inhibition since removal of even a small amount of protein by salt extraction leads to considerable loss of inhibitory activity; the detached proteins have no inhibitory activity. Although ribosomal RNA has some inhibitory activity, it is much less than that of the intact ribosomes. Reconstitution of the ribosomes from the salttreated particles and detached proteins leads to complete recovery of the inhibitory activity. This inhibition assay can be very conveniently used in measuring the purity of subunit preparations from 70 S ribosomes as well as in the study of the reconstitution of the ribosomes.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(19)44656-5