title: Identification of a nucleotide pyrophosphohydrolase from articular tissues in human serum.
abstract: OBJECTIVE
  To characterize the nucleotide pyrophosphohydrolase (NTPPHase) in human serum.
  
  
  METHODS
  NTPPHase activity and kinetic analysis were performed using thymidine monophosphate paranitrophenyl ester (TMPNP) or 32Pgamma-labeled ATP as substrate. Sera were chromatographed (dye column), and peak fractions were analyzed kinetically and by immunoblot using antibodies to 127-kd articular cartilage vesicle (ACV) NTPPHase as well as to PC-1 and to 58 kd, two plasma membrane ecto-NTPPHases. Enzyme activity was measured before and after sample ultracentrifugation.
  
  
  RESULTS
  NTPPHase activity was found in all sera tested (2 normal subjects, 9 arthritis patients). Specific activity was increased 9-32-fold after chromatography; 60-80% of total activity was recovered in a single peak containing an approximately 100-kd soluble peptide related to the 127-kd ACV enzyme. The apparent Km of this peptide (TMPNP) was virtually identical to that of the porcine ACV 127-kd enzyme. No immunoreactivity against PC-1 or 58-kd NTPPHase was found.
  
  
  CONCLUSIONS
  Human serum NTPPHase is derived from 127-kd ACV-related enzyme.
authors.affiliation: Department of Medicine, Medical College of Wisconsin, Milwaukee 53226, USA.
authors.forename: A
authors.initials: A
authors.lastname: Cardenal
authors.forename: I
authors.initials: I
authors.lastname: Masuda
authors.forename: A L
authors.initials: AL
authors.lastname: Haas
authors.forename: W
authors.initials: W
authors.lastname: Ono
authors.forename: D J
authors.initials: DJ
authors.lastname: McCarty
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002358:Cartilage, Articular / Q000201:enzymology*; D005260:Female; D006801:Humans; D015151:Immunoblotting; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D011755:Pyrophosphatases / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity; D013938:Thymidine Monophosphate / Q000031:analogs & derivatives / Q000378:metabolism; D014461:Ultracentrifugation
chemical_list: C043805:4-nitrophenyl 3'-thymidylate; D013938:Thymidine Monophosphate; D000255:Adenosine Triphosphate; D011755:Pyrophosphatases; C021895:nucleoside triphosphate pyrophosphatase