title: Arginine aminopeptidase, an integral membrane protein of the Cryptosporidium parvum sporozoite.
abstract: Cryptosporidium parvum oocysts were studied for the expression of aminopeptidase by using amino acids bound to the synthetic fluorescent substrate 7-amino-4-trifluoromethyl coumarin. After 1 h of incubation, intact oocysts showed no activity; however, homogenization and solubilization with Triton X-114 followed by phase separation yielded a 22-fold increase in aminopeptidase activity in the detergent fraction. With arginyl-6-amino-2-styrylquinoline as a substrate, aminopeptidase activity was observed in permeabilized oocysts and freshly excysted sporozoites but not on intact oocysts or empty oocyst membranes after excystation. These results suggest that C. parvum expresses an arginine aminopeptidase that is an integral protein of the sporozoite membrane.
authors.affiliation: Center for Infectious Diseases, University of Texas Health Science Center-Houston Medical School 77030.
authors.forename: P C
authors.initials: PC
authors.lastname: Okhuysen
authors.forename: H L
authors.initials: HL
authors.lastname: DuPont
authors.forename: C R
authors.initials: CR
authors.lastname: Sterling
authors.forename: C L
authors.initials: CL
authors.lastname: Chappell
mesh_terms: D000626:Aminopeptidases / Q000032:analysis* / Q000502:physiology; D000818:Animals; D016785:Cryptosporidium parvum / Q000201:enzymology*; D008565:Membrane Proteins / Q000032:analysis*; D015800:Protozoan Proteins / Q000032:analysis*
chemical_list: D008565:Membrane Proteins; D015800:Protozoan Proteins; D000626:Aminopeptidases; C019721:aminopeptidase B