An enzyme that digests RNA. First isolated from beef pancreas in 1920. Crystallization from acid extracts of pancreas: Kunitz, J. Gen. Physiol. 24, 15 (1940). Isoln: Kunitz, McDonald, Biochem. Prep. 3, 9 (1953). Bovine pancreatic RNase A is a single-chain peptide of 124 amino acid residues. Primary structure: C. H. W. Hirs et al., J. Biol. Chem. 235, 633 (1960). Amino acid sequence: D. H. Spackman et al., ibid. 648. Pictorial representation of entire structure: Stein, Moore, Sci. Am. 204, no. 2, 81-92 (Feb. 1961). Ribonuclease from plant leaves has slightly different characteristics: Markham, Strominger, Biochem. J. 64, 46P (1956). Can be obtained as a by-product of microbial erythromycin production: JP 63 26938 (1963 to Shionogi). Chemical synthesis of materials possessing partial RNase enzyme activity: Gutte, Merrifield, J. Am. Chem. Soc. 91, 501 (1969); Denkewalter, Hirschmann et al., ibid. 502. Series of articles describing the total synthesis of a protein having the full enzymic activity of bovine pancreatic RNase: N. Fujii, H. Yajima, J. Chem. Soc. Perkin Trans. 1 1981, 789-841. Specifically catalyzes the cleavage of the phosphodiester bond between the 3′ and 5′ positions of the ribose moieties in RNA with the formation of oligonucleotides terminating in 2′,3′-cyclic phosphate derivs: Roberts et al., Proc. Natl. Acad. Sci. USA 62, 1151 (1969). Reviews: Anfinsen, White, The Enzymes vol. 5, P. D. Boyer et al., Eds. (Academic Press, New York, 2nd ed., 1961) pp 95-122; Richards, Wyckoff, ibid. vol. 4 (3rd ed., 1971) pp 647-806.