Biochemical characterization of the RNA-hydrolytic activity of a pumpkin 2S albumin.

A pumpkin 2S albumin with ribonuclease (RNase) activity was purified from pumpkin seeds (Cucurbita sp.) by liquid chromatographic techniques. It manifested potent RNase activity toward baker's yeast RNA and calf liver RNA, and some polyhomoribonucleotides, including poly(A), poly(U) and poly(C) but not poly(G). Moreover, it was able to hydrolyze total RNA of both animal and plant origins. Ions such as Na(+), Mg(2+), Ca(2+), and Zn(2+) inhibited its RNase activity. Since RNase activity has not been previously reported in 2S albumins, this work may shed further light on the biological importance of this group of proteins.