Related Experiment Videos
Identification of a nucleotide pyrophosphohydrolase from articular tissues in human serum
A Cardenal1, I Masuda, A L Haas
1Department of Medicine, Medical College of Wisconsin, Milwaukee 53226, USA.
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.
Conclusion:
Human serum NTPPHase is derived from 127-kd ACV-related enzyme.