Isolation and partial characterization of amphibian tyrosine oxidase polysomes.

A population of polysomes isolated from frogskinis capable of supporting protein synthesis in a cell-free system containing an energy generating system,' soluble components', and amino acids. These polysomes catalyse the oxidation of DOPA after gentle trypsinization, and they also have antigenic determinants attributable to tyrosine oxidase. Skin polysomes sedimented in 10-30 % sucrose gradients contain tyrosine oxidase peaks of enzymic activity at the bottom and top of the tube and in the 250 S regions. A peak of tyrosine oxidase antigenic acitvity is found in the 250-350S region of the gradient. Polysomes resolved on the gradient retain the ability to support protein synthesis in a cellfree system. All 250-350S particles capable of supporting the incorporation of [C]amino acid into tyrosine oxidase are precipitable with tyrosine oxidase antibodies. It is probable that 25O-35OS tyrosine oxidase antibody precipitates contain only polysomes for this protein.