title: Purification and parital characterization of two genetic variants of placental alkaline phosphatase.
abstract: The two most common variants of placental alkaline phosphatase, the F and S variants, were purified to homogeneity and characterized. Their molecular weights were determined by equilibrium ultracentrifugation and sodium dodecylsufate polyacrylamide gel electrophoresis, which gave almost identical values for the two variants, 118,000 (F) and 119,000 (S). The amino acid compositions of F and S variants presented here are found to be very similar. Differences between the two variants were found in specific activity (160 U/mg for F and 250 U/mg for S), isoelectric point (IP - 4.5 for F and 4.7 for S),  sedimentation coefficient (6.5 X  10(-13) sec for F and 6.4 X 10(-13) sec for S). Thus the structural differences observed for these enzyme variants seem to affect both the active site and the protein conformation.
mesh_terms: D000469:Alkaline Phosphatase / Q000032:analysis* / Q000302:isolation & purification; D000596:Amino Acids / Q000032:analysis; D001665:Binding Sites; D002241:Carbohydrates / Q000032:analysis; D002848:Chromatography, DEAE-Cellulose; D005796:Genes; D014644:Genetic Variation; D006801:Humans; D007525:Isoelectric Focusing; D007527:Isoenzymes / Q000032:analysis* / Q000302:isolation & purification; D008970:Molecular Weight; D010920:Placenta / Q000201:enzymology*; D011487:Protein Conformation; D014461:Ultracentrifugation
chemical_list: D000596:Amino Acids; D002241:Carbohydrates; D007527:Isoenzymes; D000469:Alkaline Phosphatase