Alkaline Ribonuclease Associated with Polyribosomes in Fibroblasts of Experimental Granulation Tissue.

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Abstract
Alkaline ribonuclease (RNase) from polyribosomes derived from experimental rat granulation tissue was purified 1900-fold through affinity chromatography. The preparation was homogeneous in sodium dodecyl sulfate (SDS) polyacrylamide-gel electrophoresis with an estimated MW of 15,000. Purified RNase was completely inhibited in the presence of divalent ions Mg2+ (100 mM) and Ca2+ (100 mM) but activated slightly with Na+ (50 mM). The enzyme is an endonuclease. The best substrates were poly(U), mixed RNA from yeast, rRNA from granulation tissue and poly(C). The estimated apparent Km-values were 0.037, 0.064, 0.13 and 0.27 g l-1, respectively. In polyribosomes RNase occurred in both free and p-chloromercuribenzoate (pCMB)-liberated forms. The total activity was at the highest but the proportion of the free activity minimal in the granulation tissue during the maximal synthesis of collagen.