title: alpha-galactosidase A from human placenta. Stability and subunit size.
abstract: alpha-Galactosidase A (alpha-D-galactoside galactohydrolase, EC 3.2.1.22) was purified from human placenta. The purified enzyme showed one major band on polyacrylamide gel electrophoresis and a single precipitin line on double immunodiffusion. Electrophoresis of the purified, S-carboxymethylated enzyme on sodium dodecyl sulfate polyacrylamide gel showed one component with a molecular weight of about 65 000, but electrophoresis of the non-S-carboxymethylated enzyme showed two components, a major band with a molecular weight of 67 500 and a diffuse band with a molecular weight of 47 000. We suggest that the smaller diffuse component is a degradation product and that the enzyme is a dimer with a molecular weight of approximately 150 000 and a subunit of molecular weight of about 67 500. Antibody raised against the purified enzyme quantitatively precipitated alpha-galactosidase A, but not alpha-galactosidase in Fabry's disease fibroblasts. The alpha-galactosidase A is very heat labile and pH sensitive. It is most stable in concentrated solution at low temperature and at a pH of 5.0 to 6.0. When added to plasma at 37 degrees C, it has a half-life of only 17 min. This imposes a serious obstacle to its use in the treatment of Fabry's disease.
mesh_terms: D004589:Electrophoresis, Disc; D000939:Epitopes; D005260:Female; D005696:Galactosidases / Q000302:isolation & purification*; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D011489:Protein Denaturation; D000519:alpha-Galactosidase / Q000276:immunology / Q000302:isolation & purification*
chemical_list: D000939:Epitopes; D005696:Galactosidases; D000519:alpha-Galactosidase