Identification and partial purification of serum growth hormone binding protein in domestic animal species.

This study reveals the presence of growth hormone binding protein (GHBP) in domestic animals and partially purifies it from the serum of specific species. The study also highlights that the human growth hormone is a more efficient ligand than the equivalent hormone in these animals.

Objective of Research

• The primary objective of this research was to investigate the presence of growth hormone binding protein (GHBP) in domestic animals – a topic previously lacking in sufficient research.
• The research team aimed to partially purify this binding protein from the serum of different species, to study variations in serum concentrations and examine its nature and related chemical properties.

Methodology

• The study utilized a dextran-coated charcoal separation assay to demonstrate the specific binding of growth hormone (GH) in various species, namely ovine, bovine, chicken, human, goose, porcine, and equine serum, in ascending order of highest binding.
• The GHBP was then partially purified from the serum of selected species, such as chicken, ovine, and porcine, using growth hormone affinity chromatography.
• Inpects of the GHBP such as its affinity and capacity were then recorded for further analysis.
• The researchers also determined the estimated molecular weight of porcine GHBP.

Findings

• This research found significant variation in binding protein activity both within and between species. For instance, yearling ewes had higher serum GHBP concentrations than either prepubertal or older ewes.
• The purified GHBP revealed high affinity and low capacity for human GH but displayed lower binding affinity for homologous GH (GH from the same species).
• Notably, porcine GHBP had the highest affinity for human GH, while ovine GHBP had the lowest.
• Further purification of porcine GHBP resulted in an additional 1,000-fold purification, demonstrating it contains a high quantity of GHBP.
• The estimated molecular weight of the purified porcine GHBP was found to be between 50,000 to 60,000 Da.
• The results showed that the serum from all domestic species tested contained a specific GH-binding entity. Moreover, it was found that human GH was a more efficient ligand than homologous hormones.