Nov 10, 1976

Conversion of proparathyroid hormone to parathyroid hormone by a particulate enzyme of the parathyroid gland

The Journal of Biological Chemistry
R R MacGregorD V Cohn


The conversion of proparathyroid hormone (proparathormone) to parathyroid hormone (parathormone) by subcellular fractions of the bovine parathyroid has been investigated. The identification of the conversion product as parathormone was established by its elution postion during ion exchange chromatography and gel filtration, and by partial amino acid sequence analysis of its NH2-terminal region. Total homogenates and derived subcellular fractions (600 X g pellet, 5,000 X g pellet, 20,000 X g pellet, 190,000 X g pellet, and 190,000 X g supernatant) all catalyzed the conversion of exogenous [3H]- or [14C]prohormone. Over 60% of the converting activity was in the particulate fractions; the 190,000 X g particulate fraction contained the highest specific converting activity. The converting activity appeared to be an integral component of the membranes since it could only be partially removed by extraction with Triton X-100. The production of parathormone by the particulate converting enzyme increased with time and the concentration of enzyme protein. The optimum pH range was between 7 and 9, and the enzyme was inactive below pH 6. Conversion by the particulate enzyme was inhibited by benzamidine or chloroquine, but not by pancreatic ...Continue Reading

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Mentioned in this Paper

Parathyroid Hormone Peptide (1-34)
Peptide Hydrolases
Hypoparathyroidism - X-linked
Subcellular Fractions
Parathyroid Gland
Protein Precursors
Bos indicus
Hydrogen-Ion Concentration

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