The chain termini of polynucleotides formed by limited enzymic fragmentation of wheat embryo ribosomal RNA. Part 2. Studies of a snake venom ribonuclease and pancreas ribonuclease

Abstract

. [long dash]A snake venom RNase, similar to the classical pancreas RNase, can be freed of other known nucleolytic activities by acid treatment, or by acetone-f ractionation of Russell viper venom. Utilizing an end-group analytical technique in conjunction with oligo-nucleotide analyses of both partial and complete digests of ribo-nucleates, it has been possible to broadly characterize the mode of action of the snake venom RNase, even though it is present in such small amount in venom that extensive purification was not attempted. The venom RNase parallels pancreas RNase in its acid stability, pH dependence, and high degree of preferential specificity toward PypA [pyrimidine-adenosine] bonds in ribonucleate chains. Studies of the limited fragmentation of ribosomal and soluble ribonucleates, as well as dinucleoside phosphates, have shown that there are subtle differences between the venom and pancreas RNases. The results of the investigation suggest that the venom and pancreas RNases can be useful as a means of introducing a limited number of preferential scissions into ribonucleate chains at PypA internucleoside phospho-diester bonds. Incidental to the principal investigations dealing with the mode of action of the venom and pancreas RNases on ribonucleates, certain features pertaining to the nucleotide sequences in ribosomal and soluble ribonucleates from wheat embryo have been noted.