title: Partial purification and zinc dependence of human red cell pyrimidine-5'-nucleotidase.
abstract: Human red cell pyrimidine-5'-nucleotidase (EC 3.1.3.5) was partially purified from the blood of normal subjects by ion-exchange and affinity chromatography. Red cells were lysed in 50 mmol/l Tris-Cl buffer at pH 7.5 containing 1.0 mmol/l dithiothreitol and 0.5 mmol/l EDTA. The lysate was centrifuged and introduced onto a column of Sephadex A-50. After washing, the pyrimidine-5'-nucleotidase activity was eluted from the column with a NaCl gradient from 0 to 200 mmol/l in Tris buffer at pH 7.5. The pyrimidine-5'-nucleotidase was then desalted on Sephadex G-25 and introduced onto a UDP agarose column with a Tris buffer at pH 6.5 containing 150 mmol/l NaCl. This partial purification resulted in an approximately 80,000-fold increase in enzyme concentration. The Km for the partially purified enzyme was 0.32 mmol/l for UMP, 0.16 mmol/l for CMP and 0.11 mmol/l for OMP with a pH maximum of 7.5. This partially purified pyrimidine-5'-nucleotidase was then dialyzed in 50 mmol/l Tris-Cl buffer at pH 7.5 with 0.01 mmol/l CaCl2 and NaCl against 2 X 10(-3) mol/l 1,10-phenanthroline for 24 h at 4 degrees C. This incubation resulted in 73% decrease in enzyme activity which could be restored by the addition of zinc into the mixture, but not by the addition of other divalent metal ions.
mesh_terms: D015720:5'-Nucleotidase; D000328:Adult; D002846:Chromatography, Affinity; D002852:Chromatography, Ion Exchange; D004912:Erythrocytes / Q000201:enzymology*; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D009708:Nucleotidases / Q000097:blood* / Q000302:isolation & purification; D015032:Zinc / Q000502:physiology*
chemical_list: D009708:Nucleotidases; D015720:5'-Nucleotidase; D015032:Zinc