title: pH-dependent association-dissociation of high and low activity plasma alpha-L-fucosidase.
abstract: Population and family studies have confirmed the existence of a plasma alpha-L-fucosidase polymorphism in humans and the autosomal recessive inheritance of the low activity trait. The frequency of the latter is estimated at 11%. The low activity individuals or variants can also be distinguished by the fact that their plasma alpha-L-fucosidase is heat-inactivated at acidic pH. Sucrose gradient centrifugation results indicate the transition of non-variant plasma alpha-L-fucosidase with a molecular weight of 66,000 at pH 8.4 to an enzyme form with a molecular weight of 193,000 at pH 3.0. The former is thermolabile, the latter thermostable. Interconversion is pH-dependent. It is hypothesized that the non-variant enzyme, a monomer at alkaline pH, changes upon acidification into a trimeric conformation via dimerization. The thermolabile variant alpha-L-fucosidase monomer is not converted into a trimer, but only partially into a dimer.
mesh_terms: D005787:Gene Frequency; D005808:Genes, Recessive; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D010641:Phenotype; D011110:Polymorphism, Genetic; D005644:alpha-L-Fucosidase / Q000032:analysis / Q000235:genetics* / Q000378:metabolism
chemical_list: D005644:alpha-L-Fucosidase