Novel specificity of an endoribonuclease of yeast

Investigations of the cleavage specificity of a cyclizing endoribonuclease of yeast show that it hydrolyzes Y-A bonds of single-stranded regions of RNA and that oligonucleotides are hydrolyzed poorly. The stringent specificity of the enzyme suggests that it may be useful for generating specific fragments of polyribonucleotides. An isolation technique employing ethanol extraction has now been used to isolate the enzyme free of other RNases, and the studies show that it is a small protein, 10 kDa or less in molecular mass.