1978 Volume 69 Issue 10 Pages 1349-1354
It was reported in the previous report that RNA was a principal calcium oxalate crystal growth inhibitor in rat liver. From the comparison of inhibitory activity of RNA with DNA or 4 kinds of homopoly nucleotides, the OH group in 2' position of ribose was found to be important for the activity. That the inhibitory properties of RNA were dependent on the intactness of the chain became clear from the following two experiments. 1) Alkali hydrolysis of RNA diminishes or destroys the activity according to the degree of hydrolysis. 2) Sephadex G-50 column chromatography of partially digested RNA by RNases showed that the fragment eluted in the salt volume was inactive. Because poly-L-aspartic acid and poly-L-glutamic acid have these two properties, they were tested for their activity and found to be very strong inhibitors. Polymer of aspartic acid was especially active. To be high molecular weight substances and to have free OH or -COOH groups are apparently the general requirements for inhibitors. The number of monomeric unit to make a polymer or oligomer active is not known and the study is now under way.
