The mechanism of action of polynucleotide phosphorylase.

The purpose of this paper is to review certain aspects of the mechanism of action of polynucleotide phosphorylase and to present, rather briefly, some recent findings. The discussion will be concerned with studies carried out by S. Ochoa and his associates a t New York University, New York, N. Y., and with work done a t the National Institutes of Health. Reference will also be made to some recent work carried out in Bethesda by Grunberg-Manago. Some of the material to be presented has already been published, but a review may be profitable at this time. Certain of the unsolved problems that face investigators in this field also will be discussed. Polynucleotide phosphorylase was discovered by Grunberg-Manago and Ochoa in extracts of Azotobacter agile.’r2 Studies of the nature of nucleotide incorporation into nucleic acid in Escherichia coli led to a recognition of the same reaction by Littauer and Rornberg.3, 4 , Beers6 has made extensive studies of the enzyme from Micrococcus lysodeikticus, and some of this work will be presented in another paper in this symposium. Olmsted’ has also reported studies dealing with polynucleotide phosphorylase from M . lysodeikticus. The reaction catalyzed by the enzyme may be formulated as follows: