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A group of enzymes, widely distributed in nature, which catalyze hydrolysis of the internucleotide phosphodiester bonds in ribonucleic acid (RNA). The sites of hydrolysis may vary considerably, depending upon the specificity of the particular enzyme. Differences in specificity for the site of cleavage have led to the use of these various ribonucleases as tools in determining the structure and chemistry of RNA. See Enzyme, Nucleic acid

Research on ribonuclease has played a prime role in advancing the understanding of protein structure and function; also, it was the first protein to be totally synthesized from its component amino acids. Since the elucidation of the amino acid sequence of ribonuclease, much information has been compiled with regard to the three-dimensional structure of the enzyme and to specific regions of the molecule which are catalytically important. See Protein



an enzyme that depolymerizes ribonucleic acids and synthetic ribonucleotides by breaking the phosphodiester bonds of polynucleotide chains. Ribonucleases exhibit a high specificity in relation to the bases contained in nucleotides; the bonds between different nucleotides are hydrolyzed by different ribonucleases.

Pancreatic ribonuclease secreted by the pancreas of a bull was the first enzyme for which the primary structure, that is, the sequence of amino acids, was fully established (1960–62). The polypeptide chain of this enzyme consists of 124 amino-acid residues and contains four disulfide bridges that stabilize the enzyme’s spatial configuration. Pancreatic ribonuclease was first chemically synthesized in 1969.

In biochemical research ribonucleases are used in establishing the sequence of nucleotides in RNA, and in medicine they are used in treating certain viral diseases.


Khimiia biologicheski aktivnykh prirodnykh soedinenii. Moscow, 1970.
Nukleazy mikroorganizmov. Moscow, 1974.


C587H909N171O197S12 An enzyme that catalyzes the depolymerization of ribonucleic acid.