Studies on Alkaline RNA-hydrolyzing Enzyme in the Pyloric Caeca of Rainbow Trout

Abstract

Though a large number of nucleases have been investigated, little is known about the enzymes in fish. The present investigation was undertaken to elucidate the property and function of the nucleases in fish. As a first step in this programme, the RNA-hydrolyzing enzyme in the pyloric caeca of rainbow trout was studied. The frozen pyloric caeca was homogenized in 10 volumes of 0.25M sucrose solution, and the homogenate was filtered through a gauze. The filtrate was used as the enzyme solution. The enzyme activity was estimated from readings obtained for absorbance at 260mμ of the acid soluble degradates from RNA. In the pyloric caeca of rainbow trout, two kinds of RNA-hydrolyzing activities were observed. One of the activities was observed at the acidic pH (pH optimum 5.5) and the other at the alkaline pH (pH optimum 8.75). In this report, some properties of the alkaline RNA-hydrolyzing enzyme are described. The activity level of the enzyme is similar to that of the enzyme found in rat pancreas. This enzyme is very labile, but in the presence of Ca⁺⁺, the enzyme gets stabilized specifically to pH and heat. The enzyme is characterized by its marked stabilization with Ca⁺⁺