Isolation and characterization of turkey prolactin

Abstract

Prolactin from frozen turkey pituitary glands was purified by alkaline ethanol extraction of the pituitary residue after pre-extractions of the gonadotrophins and GH, followed by gel filtration on Sephadex G-100 and DEAE-cellulose column chromatography at different pH. A specific radioligand--receptor assay for ovine prolactin was used to locate the activity in eluates after column chromatography and gel filtration. The potency of the highly purified turkey prolactin was characterized by a radioligand--receptor assay to be 3.40 i.u./mg and by a heterologous radioimmunoassay to be 35 i.u./mg as compared to purified ovine prolactin as standard. The yield of turkey prolactin was 3 mg/100 g frozen pituitary glands. The purified turkey prolactin consisted of three protein bands upon polyacrylamide gel electrophoresis and the molecular weight was estimated to be 22000 by SDS--polyacrylamide gel electrophoresis. Turkey prolactin was rich in aspartic acid, glutamic acid and leucine, but lacking in methionine.