MODE OF ACTION AND BASE SPECIFICITY OF A NUCLEASE FROM SILKWORM

The silkworm nuclease [EC class 3. 1. 4] had no definite base specificity but shown only a slight base preference. This enzyme attacked RNA in an endonucleolytic manner. The rate of enzyme reaction was influenced by the chain length rather than the nature of bases in substrate and was very slow when the substrate reached a critical chain length. Digestion of RNA with an excess of the nuclease produced exclusively mono-, di- and trinucleotides. Of the mononucleotide fraction, 5'-guanylic acid predominated over the other three.This enzyme may be a useful reagent in the structural studies on RNA. © 1968 by the Journal of Biochemistry.