Aminopeptidase P and dipeptidyl peptidase IV activity in human leukocytes and in stimulated lymphocytes.
Human white blood cells were shown to contain high aminopeptidase P activity. The specific activities found in the high-speed supernatant of the extracts of granulocytes, lymphocytes and monocytes ranged from 30 to 70 units per mg protein. Culturing lymphocytes during 7 days in the presence of phytohaemagglutinin resulted in a 70-200% increase in the specific aminopeptidase P activity and a 200% increase in the specific activity of dipeptidyl peptidase IV. The time-course of the activity of both aminopeptidase P and dipeptidyl peptidase IV during the stimulation of human T-lymphocytes by phytohaemagglutinin indicates an involvement of these two enzymes in the proliferative process of these immunocompetent cells. Due to their substrate specificity their potential substrates must have the N-terminal Xaa-Pro sequence known to be present in several immunologically important polypeptides.
Hendriks
D
D
Department of Biophysics, Weizmann Institute of Science, Rehovot, Israel.
De Meester
I
I
Umiel
T
T
Vanhoof
G
G
van Sande
M
M
Scharpé
S
S
Yaron
A
A
D000626:Aminopeptidases / Q000097:blood*; D002457:Cell Extracts; D002499:Centrifugation, Density Gradient; D018819:Dipeptidyl Peptidase 4; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000097:blood*; D006801:Humans; D007531:Isoflurophate / Q000378:metabolism; D007962:Leukocytes / Q000201:enzymology*; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000201:enzymology*; D010835:Phytohemagglutinins / Q000494:pharmacology
D002457:Cell Extracts; D010835:Phytohemagglutinins; D007531:Isoflurophate; D000626:Aminopeptidases; C022750:X-Pro aminopeptidase; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D018819:Dipeptidyl Peptidase 4