Characterization of immunoreactive dynorphin B and beta-endorphin in human plasma.
Dynorphins and beta-endorphin in human plasma were characterized and studied quantitatively using radioimmunoassay, high-performance liquid chromatography (HPLC), and mass spectrometry. Most immunoreactive (ir) dynorphin B and beta-endorphin in human plasma coeluted with authentic peptides in analysis. Dynorphin A was not detected. Added to human plasma it was rapidly converted into Leu-enkephalin-Arg6 followed by elimination of the C-terminal arginine after prolonged incubation. The rate of dynorphin A conversion was estimated at 40 pmol/min/microl plasma. This process was inhibited by the thiol protease inhibitor, PHMB and by EDTA. Dynorphin B, alpha-neoendorphin and big dynorphin were virtually not metabolized by plasma proteases under the same conditions. beta-endorphin was processed into beta-endorphin(1-19) and the corresponding C-terminal counterpart beta-endorphin(20-31) at a rate of about 25 pmol/min/microl of plasma. Based on the above data, a reliable strategy was established to measure dynorphin B- and beta-endorphin-ir in human plasma samples. The basal levels in a male control group were 0.99 +/- 0.11 (n = 11) and 16.3 +/- 1.5 (n = 11) fmol/ml plasma, respectively.
Silberring
J
J
Faculty of Chemistry, Jagiellonian University, Krakow, Poland.
Li
Y M
YM
Terenius
L
L
Nylander
I
I
D000328:Adult; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004399:Dynorphins / Q000097:blood* / Q000737:chemistry; D010450:Endopeptidases / Q000378:metabolism; D004723:Endorphins / Q000097:blood* / Q000737:chemistry; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D009479:Neuropeptides / Q000097:blood; D010446:Peptide Fragments / Q000097:blood; D011480:Protease Inhibitors / Q000378:metabolism; D011863:Radioimmunoassay / Q000379:methods; D001615:beta-Endorphin / Q000097:blood* / Q000378:metabolism
D004723:Endorphins; D009479:Neuropeptides; D010446:Peptide Fragments; D011480:Protease Inhibitors; D001615:beta-Endorphin; D004399:Dynorphins; C036200:rimorphin; D010450:Endopeptidases