title: Purification and characterization of adenine phosphoribosyltransferase from mouse mammary carcinoma FM3A cells in culture.
abstract: Adenine phosphoribosyltransferase has been purified to apparent homogeneity from mouse mammary tumor FM3A cells. The purified enzyme, with a specific activity of 20.6 X 10(6) units/g protein at 30 degrees C, was homogeneous as judged by polyacrylamide gel electrophoresis and Ouchterlony double immunodiffusion analysis. The native enzyme had a molecular weight of 44,000 and a subunit composition of 23,000. Apparent Km values for adenine and 5-phosphoribosyl-1-pyrophosphate (PRib-PP) were 6.6 microM and 1.2 microM, respectively. Free Mg2+ was an essential activator with a half-maximal effect at 0.4 mM. AMP was an inhibitor, competitive with PRib-PP, and the Ki value was estimated to be 24 microM. The enzyme activity was not significantly affected by 2,6-diaminopurine, 4-carbamoylimidazolium 5-olate, 8-azaadenine, and 2-fluoro-6-aminopurine. An antibody against the purified mouse adenine phosphoribosyltransferase was raised in a rabbit. The enzyme derived from either mouse, Chinese hamster, or human cells was completely neutralized and precipitated by this antibody, indicating that these enzymes share a common antigenic determinant.
mesh_terms: D000228:Adenine Phosphoribosyltransferase / Q000302:isolation & purification*; D000818:Animals; D002384:Catalysis; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D007120:Immunochemistry; D008325:Mammary Neoplasms, Experimental / Q000201:enzymology*; D051379:Mice; D008970:Molecular Weight; D010430:Pentosyltransferases / Q000302:isolation & purification*
chemical_list: D010430:Pentosyltransferases; D000228:Adenine Phosphoribosyltransferase