Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

In cultured monolayers of human articular chondrocytes we have observed an enzyme activity which catalyzes the extracellular conversion of ATP to AMP and PPi. The enzyme was active at very low concentrations of ATP (microM) and exhibited optimal activity at concentrations of ATP of approx. 100 microM. The enzyme was active in intact cells as judged by measurement of the release of the cytoplasmic marker enzyme lactate dehydrogenase. No increase in production of PPi from ATP was observed on mechanically disrupting the cells and no activity was shed into the medium by intact cells. Activity was stable between days 4 and 8 after subculturing the cells and was not affected by the timing of the final medium change prior to assay. Activity was also observed with other nucleoside triphosphates (GTP, CTP and UTP). We suggest that this activity is attributable to ecto-nucleoside triphosphate pyrophosphatase. This observation may be important in relation to the pathogenesis of the human disease of chondrocalcinosis in which crystals of calcium pyrophosphate dihydrate deposit in articular cartilage.

Original publication

DOI

10.1016/0167-4889(85)90150-8

Type

Journal article

Journal

Biochim biophys acta

Publication Date

30/10/1985

Volume

847

Pages

40 - 47

Keywords

Adenosine Triphosphate, Cartilage, Articular, Cells, Cultured, Cytidine Triphosphate, Diphosphates, Guanosine Triphosphate, Humans, Kinetics, Pyrophosphatases, Uridine Triphosphate