angiotensin-i and 3-4-dehydroproline

3,4-dehydroproline9-GnRH prepared by solid phase peptide synthesis was tritiated catalytically under various conditions yielding 3H-GnRH with specific radioactivities in the range from 35-60 Ci/mmol and full LH releasing activity in vitro. Using palladium/alumina catalyst, the tritiation of the double bond occurs within ten minutes. Investigation of the tritium distribution between the amino acid residues showed a remarkably high incorporation of tritium into the histidine residue (11 to 37%). On the basis of this observation, the tritium labeling of GnRH and angiotensin I by direct catalytic hydrogen-tritium exchange was found to be useful for the labeling of these peptides at remarkably high specific radioactivity.

Topics: Aluminum Oxide; Angiotensin I; Animals; Catalysis; Gonadotropin-Releasing Hormone; Half-Life; Histidine; Isotope Labeling; Palladium; Pituitary Gland; Proline; Rats; Tritium