A 5'-phosphodiesterase of the streptomyces species

The flavor enhancing property of inosine-5-phosphate (5’-IMP) was first reported by Kodama in 1913 (23). Batzer and LandMann (7) also identified this compound as one of the important beef flavor precusors. Kuninaka (24) from his studies on the characteristics of 5’-ribomononucleotides found that guanosine-5-phosphate and xanthine-5-phosphate also had a seasoning effect similar to 5'-IMP.

Snake venom (21) and intestinal mucosa (13) were known as sources of 5'-phosphodiesterase which was able to catalyze the cleavage of phosphate ester linkage of RNA to produce 5'-ribomononucleotides. However, it has been discovered recently (25, 33, 35) that many microorganisms also capable of producing 5'-phosphodiesterase and of degrading nucleic acid into 5'-nucleotides. Therefore, the production of 5'-mononucleotides by means of a microbial enzyme has become possible.

With these ideas in mind, a microorganism was isolated from soil and this study was made in an attempt:

(1) to identify the microorganism which is capable of degrading ribonucleic acid (RNA) into 5'-ribomononucleotides; (2) to identify the variety of 5’-ribomononucleotides produced from the hydrolysis of RNA by this organism.