title: Biological variation of rabbit chondrocyte 5'nucleotidase.
abstract: The activity of 5'nucleotidase was investigated in rabbit chondrocytes. Studies of chondrocytes in organ culture and intact cells revealed that ecto-5'nucleotidase activity varies with the age of the animal. Specific activities of 0.29, 0.62, 1.97, and 1.39 mumole/hr/10(6) cells were observed in intact cells from 3-week-, 3-month-, 6-month-, and 2-year-old animals. Specific activities of 15.5, 33.1, 80.3, and 39.5 mumole/hr/mg protein, respectively, were observed when the enzyme protein was solubilized from disrupted cells with the detergent octyl-beta-D-glucopyranoside. Membrane-bound nonspecific neutral phosphatase activity did not vary with age. Activity of 5'nucleotidase was observed on all chondrocytes using a histochemical staining technique. Kinetic properties of the enzyme from animals of different ages were investigated. No differences were noted in apparent Km value for AMP (23 microM), pH optima (7.3), substrate competition studies, and effects of MgCl2 or CaCl2. These data demonstrate a biological variation in rabbit chondrocyte 5'nucleotidase activity with age. The variation of activity represents an apparent increase in the amount of enzyme protein rather than an alteration in kinetic properties.
mesh_terms: D015720:5'-Nucleotidase; D000375:Aging; D000818:Animals; D002358:Cartilage, Articular / Q000201:enzymology*; D005960:Glucosides; D006651:Histocytochemistry; D007700:Kinetics; D009708:Nucleotidases / Q000378:metabolism*; D009924:Organ Culture Techniques; D011817:Rabbits
chemical_list: D005960:Glucosides; C018619:octyl-beta-D-glucoside; D009708:Nucleotidases; D015720:5'-Nucleotidase