Title: Polynucleotide Phosphorylase of Micrococcus luteus (Micrococcus lysodeikticus)
Abstract:Abstract Polynucleotide phosphorylase of Micrococcus luteus (formerly Micrococcus lysodeikticus) is converted to a primer-dependent form by limited tryptic hydrolysis. Evidence is presented which indi...Abstract Polynucleotide phosphorylase of Micrococcus luteus (formerly Micrococcus lysodeikticus) is converted to a primer-dependent form by limited tryptic hydrolysis. Evidence is presented which indicates that the loss of a portion of the polypeptide is not itself responsible for the loss of ability to initiate polymerization. Thus, the primer-dependent enzyme obtained after tryptic hydrolysis is converted to primer-independent enzyme by reduction with sulfhydryl reagents. It can then be reconverted to primer dependence by reaction with sulfhydryl inhibitors. Under suitable conditions these treatments have a selective effect on the ability of the enzyme to polymerize ADP in the absence of primer. Neither the ability to phosphorolyze polyribonucleotide nor the ability to polymerize in the presence of primer is markedly affected. Therefore it appears that the tryptic hydrolysis is accompanied by the modification of one or more sulfurcontaining amino acids. This modification is incompatible with polymerization unless a primer is present. Preliminary experiments on the nature of these residues in the original enzyme are also presented.Read More