Translocation of mRNA codons. I. The preparation and characteristics of a homogeneous enzyme.

This report describes a convenient scheme for the further purification of an E. coli enzyme which is required for the translocation step in protein biosynthesis. The homogeneous enzyme translocase appears to be a relatively large monomeric protein, having a molecular weight of approximately 72,000, and acts in a catalytic fashion during protein synthesis. It is also one of the major soluble macromolecular constituents of rapidly growing E. coli, comprising more than 2 per cent of the protein in ribosome-free extracts. Further, the rate of in vitro protein synthesis is linearly dependent upon the concentration of the pure enzyme until approximately one molecule of translocase is present per ribosome in reaction mixtures.