Tyrosinase from embryonic chick retinal pigment epithelium

Abstract

1. 1. Twenty per cent of tyrosinase activity in 14-day chick embryo retinal pigment epithelium is found in the soluble fraction and 80 per cent is in the large particle fraction. 2. 2. Digitonin and sodium deoxycholate treatment release particulate tyroinase into the supernantant in forms having molecular weights of 140 × 10 3 and 220 × 10 3, respectively. 3. 3. The soluble fraction of chick embryo pigment cells contains two forms of tyrosinase with molecular weights of 72 × 10 3 and 150 × 10 3. 4. 4. All forms of tyrosinase observed in chick retinal pigment cells have molecular weights which are integral multiples of approximately 72 × 10 3. Implications of these results are discussed in relation to multiple forms of tyrosinase in other vertebrates, especially the mouse.