A comparison of human lung, brain, CSF and plasma angiotensin-converting enzyme with regard to neuropeptide metabolism.
Human ACE obtained from different tissues and body fluids was assayed with regard to degradative action on tachykinins and various opioid peptides. Substance P (1-9) was easily cleaved, whereas substance P and neurokinin A seemed stable against ACE activity. However, endopeptidase-24.11 easily degraded both of these amidated peptides. When the same peptides were assayed as potential inhibitors of the hydrolysis of hippuryl-His-Leu (specific substrate for ACE activity), substance P and its (1-9) fragment were equally potent, whereas neurokinin A was inactive. The beta-casomorphins, beta-casein derived opioid peptides, with a proline residue at their C-terminus also showed inhibitory action on ACE activity, without being cleaved by the enzyme. These results indicate a modulatory action of these peptides. No differences between ACE originating from different tissues or body fluids could be demonstrated in this regard.
Lantz
I
I
Department of Pharmacology, University of Uppsala, Sweden.
Thörnwall
M
M
Kihlström
J E
JE
Nyberg
F
F
D000595:Amino Acid Sequence; D001921:Brain / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004727:Endothelium / Q000201:enzymology; D006801:Humans; D008168:Lung / Q000378:metabolism*; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D015260:Neprilysin / Q000378:metabolism; D009474:Neurons / Q000201:enzymology; D009479:Neuropeptides / Q000378:metabolism*; D007703:Peptidyl-Dipeptidase A / Q000097:blood / Q000134:cerebrospinal fluid / Q000378:metabolism*
D009479:Neuropeptides; D007703:Peptidyl-Dipeptidase A; D015260:Neprilysin