Endopolyphosphatase activity of RNase A from bovine pancreas

Inorganic polyphosphate preparations from various biological samples often contain significant RNA contamination, complicating their analysis. The standard method for purifying such preparations from RNA is the treatment with RNases, particularly RNase A. This study demonstrated that commercial preparation of RNAse A, at concentrations used to purify polyphosphate preparations from RNA, exhibits endopolyphosphatase activity against polyphosphates with an average chain length of 65 to 208 phosphate residues, but does not exhibit exopolyphosphatase activity. This activity is inhibited by ribonuclease inhibitor, insensitive to the polyphosphatase inhibitor heparin and does not require divalent metal cations.