Isolation and characterization of turkey prolactin

Area of Science:

• Endocrinology
• Protein Chemistry
• Comparative Physiology

Background:

• Prolactin is a crucial hormone involved in reproduction and metabolism.
• Purification of avian prolactin is essential for understanding its specific functions.
• Previous studies have focused on mammalian prolactin, leaving avian prolactin less characterized.

Purpose of the Study:

• To develop an effective purification protocol for turkey prolactin.
• To characterize the biochemical and biological properties of purified turkey prolactin.
• To establish a reliable method for quantifying turkey prolactin potency.

Main Methods:

• Alkaline ethanol extraction of turkey pituitary glands.
• Sequential purification using gel filtration (Sephadex G-100) and ion-exchange chromatography (DEAE-cellulose).
• Activity identification via radioligand-receptor assay for ovine prolactin.
• Potency determination using radioligand-receptor and radioimmunoassay methods.
• Molecular weight and purity assessment by SDS-polyacrylamide gel electrophoresis.

Main Results:

• Successfully purified turkey prolactin with a yield of 3 mg/100 g of pituitary glands.
• Characterized turkey prolactin potency as 3.40 i.u./mg (radioligand-receptor assay) and 35 i.u./mg (radioimmunoassay) relative to ovine prolactin.
• Electrophoresis revealed three protein bands, with an estimated molecular weight of 22,000 Da; the amino acid profile showed richness in aspartic acid, glutamic acid, and leucine, and a lack of methionine.

Conclusions:

• An efficient method for purifying turkey prolactin was established.
• The purified turkey prolactin exhibits distinct biochemical properties.
• This purified hormone serves as a valuable resource for further studies on avian prolactin's physiological roles.