Exopeptidases in human platelets: an indication for proteolytic modulation of biologically active peptides.
The determination in human platelets of four exopeptidases--aminopeptidase P, dipeptidyl peptidase IV, carboxypeptidase N, and angiotensin converting enzyme--by means of fluorometric or liquid chromatography techniques was carried out. The results obtained show that the specific activities of dipeptidyl peptidase IV, carboxypeptidase N, and angiotensin converting enzyme in intact and disrupted platelets are small compared to their specific activities in serum. However, for aminopeptidase P the specific activity of this enzyme is much higher in platelets than in serum. This suggests that circulating platelets may have a significant role as scavengers for circulating peptides containing bonds susceptible for aminopeptidase P.
Scharpé
S L
SL
Department of Clinical Biochemistry, University of Antwerp, Belgium.
Vanhoof
G C
GC
De Meester
I A
IA
Hendriks
D F
DF
van Sande
M E
ME
Muylle
L M
LM
Yaron
A
A
D000626:Aminopeptidases / Q000097:blood*; D001792:Blood Platelets / Q000201:enzymology*; D018819:Dipeptidyl Peptidase 4; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000097:blood*; D006801:Humans; D001121:Lysine Carboxypeptidase / Q000097:blood*; D007703:Peptidyl-Dipeptidase A / Q000097:blood*
D000626:Aminopeptidases; C022750:X-Pro aminopeptidase; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D018819:Dipeptidyl Peptidase 4; D007703:Peptidyl-Dipeptidase A; D001121:Lysine Carboxypeptidase