Nucleoside; widely distributed in nature. Prepd by hydrolysis of yeast nucleic acid with weak alkali, cf. Levene, Bass, Nucleic Acids (New York, 1931). Improved isolns: Harris, Thomas, J. Chem. Soc. 1948, 1936; Elmore, ibid. 1950, 2084; Lorine, Ploeser, J. Biol. Chem. 178, 439 (1949). Crystal structure: Green et al., Chem. Commun. 1971, 53. Review: Basic Principles in Nucleic Acid Chemistry vol. 1, P. O. P. Ts'o, Ed. (Academic Press, New York, 1974) passim.