NTP pyrophosphohydrolase in human chondrocalcinotic and osteoarthritic cartilage. I. Some biochemical characteristics

Nucleoside triphosphate pyrophosphohydrolase activity was first detected in articular cartilage in previous studies at our laboratory. In this report, the enzyme is partially characterized with respect to its pH optimum and Km. The enzyme was metal-dependent and was active in the presence of 1 mM Ca++. It was inhibited by several substances, including cysteine and dithiothreitol. Its activity was not inhibited by tetramisole at concentrations which inhibited 100% of the pyrophosphatase activity in the same extracts. It functioned most effectively on ATP, but also on UTP, CTP, and GTP. A role for scavenging nucleotides and production of pyrophosphate in osteoarthritic and chondrocalcinotic cartilage is postulated.