Isolation and amino acid sequence of the alpha-subunit of follicle-stimulating hormone from equine pituitary glands.

The researchers extracted Follicle-Stimulating Hormone (FSH) from horse pituitary glands, broke it down into its alpha and beta subunits, and identified the sequence of amino acids in the alpha subunit. They found differences between the alpha subunit of horse FSH and those of human FSH and cow Thyroid-Stimulating Hormone.

Isolation of Follicle-Stimulating Hormone (FSH)

• The researchers began their experiment by isolating 600 milligrams of FSH from 9 kilograms of equine pituitary glands.
• They managed to isolate an FSH mixture with a high level of activity, as indicated by the measurement of 110 NIH-FSH-S1 units per milligram.

Dissociation of the FSH Into Subunits

• Once the FSH was isolated, the researchers dissociated it into its two primary subunits: the alpha- and beta-subunits. This was achieved through laboratory techniques specific to peptide and protein analysis.

Amino Acid Sequence Determination for the Alpha-Subunit

• Following the dissociation of FSH into its component parts, the researchers determined the sequence of amino acids forming the alpha-subunit.
• They found that the alpha-subunit contained a total of 82 amino acids.

Comparison with Other Hormone Alpha-Subunits

• The sequence of amino acids in the alpha-subunit of the equine (horse) FSH was compared with those found in human FSH and bovine (cow) Thyroid-Stimulating Hormone.
• It was discovered that the equine alpha-subunit was shorter by 10 to 14 amino acids at one end (the NH2 terminus) compared to its human and bovine counterparts. There were also several substitutions at different positions within the sequence.

Intraspecies and Interspecies Differences

• When comparing alpha-subunits within the same species (intraspecies), the human FSH, Luteinizing Hormone, and Chorionic Gonadotropin were found to be relatively similar.
• However, when comparing between species (interspecies), there were distinct differences among the alpha-subunits of FSH, Luteinizing Hormone, and Thyroid-Stimulating Hormone.