Dipeptidyl peptidase IV (DP IV) and superoxide dismutase activity in thymus-derived lymphocytes: effects of inhibitory peptides and Zn2+ in vitro.
DP IV and superoxide dismutase (SOD) activity in thymus-derived lymphocytes of rats was assayed in vitro. The DP IV activity was measured fluorimetrically by hydrolysis of Leu-Pro-AMC, and the SOD activity by the inhibition of autooxidation of L-adrenaline. In order of their competitive inhibitory potency the following peptides were tested against DP IV and SOD activity: Ile-Pro-Ile (diprotin A), Val-Pro-Leu (diprotin B), Ile-Pro, Leu-Pro, Val-Pro, Tyr-D--Ala-Ala-Pro, Phe-Pro, Tyr-Pro, Ala-Ala-Pro and Gly-Pro. The peptides, in the order of their potency against DP IV, were effective to inhibit the SOD activity in T lymphocytes. Zn2+ ions exerted an inhibition on both DP IV and SOD activity in a near equimolar concentration. The involvement of Zn2+ as well as the peptides liberated by hydrolysis of polypeptides in regulation of cell-mediated immune responses has been discussed.
Endröczi
E
E
Institute of Clinical and Experimental Laboratory Investigations, University of Postgraduate Medical Education, Budapest, Hungary.
Hepp
J
J
Sasváry
M
M
Walentin
S
S
Lévay
G
G
D000595:Amino Acid Sequence; D000818:Animals; D018819:Dipeptidyl Peptidase 4; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000037:antagonists & inhibitors / Q000097:blood*; D008297:Male; D008969:Molecular Sequence Data; D010455:Peptides / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013482:Superoxide Dismutase / Q000037:antagonists & inhibitors / Q000097:blood*; D013601:T-Lymphocytes / Q000201:enzymology*; D015032:Zinc / Q000494:pharmacology*
D010455:Peptides; D013482:Superoxide Dismutase; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D018819:Dipeptidyl Peptidase 4; D015032:Zinc