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Abstract
Abstract A new procedure is described for the isolation on a preparative scale of a hypothalamic decapeptide which stimulates the release of both luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary. The isolation was achieved mainly by countercurrent distribution. The yield from 240,000 porcine hypothalami was 11.4 mg. Thin layer chromatography and electrophoresis showed the material to be homogeneous. The amino acid analyses showed the presence of 2 residues of glycine and 1 residue each of histidine, arginine, tryptophan, serine, glutamic acid, proline, leucine, and tyrosine. This decapeptide stimulates release of both LH and FSH in vivo as well as in vitro in doses smaller than 1 ng. It is thought to be the hypothalamic hormone which controls secretion of both LH and FSH from the pituitary gland.
Highlights
This paper describes a new isolation procedure for luteiaizing hormone (LH)-RH/
It, is possible that in many of the steps used in previous work, some of which employed columns packed with cellulose derivatives and Sephadex for ion exchange chromatography, partition chromatography, and electrophoresis, signficant losses of LH-RH/folliclestimulating hormone (FSH)-RI-1 occurred by adsorption on column materials
The yield of LH-RH in the case of either method is many times greater than that reported for ovine LH-RH, in spite of the fact that sheep hypothalamic tissue may have a much higher initial LH-RH content than porcine tissue [22]
Summary
Dissection and Extraction-Fragments of porcine ventral hypothalami consisting mainly of the pituitary stalk and median eminence were dissected, frozen on Dry Ice, and lyophilized by the staff of Oscar Mayer and Company, Madison, Wisconsin. The lyophilized hypothalami were shipped to our laboratory, where they were pulverized on Dry Ice, defatted with acetone and petroleum ether (40-60”), and extracted with 2 N acetic acid at 8”. Gel Filtration on Sephadex-Since t,he glacial acetic acid reextraction [4, 8] of lyophilized extracts did not lead to significant concentration of activity in the case of this particular batch, this step was omitted. The lyophilized 2 N acetic acid extracts were suspended in 1 N acetic acid, centrifuged at 30,000 x g, and subjected to molecular sieving on a large column of Sephadex G-25
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