Purification and some properties of a membrane-bound dipeptidyl peptidase IV of guinea pig casein-induced intraperitoneal leukocytes.
Dipeptidyl peptidase IV [EC 3.4.14.5] (DPP-IV) was demonstrated to exist in guinea pig casein-induced, peritoneal polymorphonuclear leukocytes (PMN) as well as contaminating macrophages and lymphocytes through the use of glycyl-L-prolyl-4-methylcoumaryl-7-amide (Gly-Pro-MCA) as a substrate. The DPP-IV of PMN was found to be located both on the plasma membrane and in the cytosol. For characterization, the plasma membrane-bound enzyme isolated from peritoneal cells mainly consisting of PMN was solubilized with 0.1% Triton N101 and purified by DEAE-cellulose chromatography, gel filtration, and affinity chromatographies on concanavalin A-Sepharose 4B and Gly-Pro-Sepharose 4B. The purification was more than 570-fold. The purified enzyme appears to be a noncovalent dimer of the 158K dalton DPP-IV. The pH optimum, isoelectric point and Km value for Gly-Pro-MCA were 7.2, 5.5, and 2.0 X 10(-4)M, respectively. The enzyme was inactivated by diisopropyl fluorophosphate and diprotin A. It was capable of cleaving dipeptidyl-MCA of an X-Pro-MCA type (X: free N-terminal amino acid). These properties are similar to those of DPP-IV purified from other tissues.
Kudo
M
M
Nakamura
T
T
Koyama
J
J
D000818:Animals; D002364:Caseins / Q000494:pharmacology; D002462:Cell Membrane / Q000201:enzymology; D018819:Dipeptidyl Peptidase 4; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D010450:Endopeptidases / Q000302:isolation & purification*; D006168:Guinea Pigs; D008214:Lymphocytes / Q000201:enzymology; D008264:Macrophages / Q000201:enzymology; D009504:Neutrophils / Q000201:enzymology*; D013347:Subcellular Fractions / Q000201:enzymology; D013379:Substrate Specificity
D002364:Caseins; D010450:Endopeptidases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D018819:Dipeptidyl Peptidase 4