title: Biochemical and immunochemical characterization of hexosaminidase P.
abstract: Hexasaminidase P, the main isozyme of hexosaminidase in pregnancy serum, was isolated and purified 600--700-fold by a two-step purification procedure--affinity chromatography on Sepharose-bound epsilon-aminocaproyl-N-acetylglucosylamine, followed by ion-exchange chromatography on DEAE-cellulose. The purified enzyme was subjected to biochemical and immunochemical analysis. Its catalytic property, namely, kinetic behavior, is similar to that of the major isozymes of hexosaminidase, A and B. However, it differs from these isozymes in its electrophoretic mobility and in its apparent molecular weight which is around 150 000 compared with 100 000 of the A and B isozymes. Immunochemical analysis indicates that the P isozymes is antigenically cross-reactive with both A and B isozymes, but it does not contain the A-specific antigenic determinants, and exhibits identical antigenic specificity to hexasaminidase B. Two possible structures are suggested that are compatible with the experimental data: (a) a hexosaminidase B like structure with higher extent of glycosylation; (b) a hexameter of beta chain, possibly arranged as three beta2 subunits.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D000939:Epitopes; D005260:Female; D006596:Hexosaminidases / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy
chemical_list: D000939:Epitopes; D007527:Isoenzymes; D046911:Macromolecular Substances; D006596:Hexosaminidases