Characterization of an Anti-β-galactosidase Antibody Recognizing a Precursor But Not a Mature Enzyme in Solution

Abstract A monospecific antibody was raised against a recombinant human 84-kDa β-galactosidase precursor protein, which had been produced with a baculovirus gene expression system and affinity-purified. It bound to the 64-kDa mature enzyme protein extracted from human fibroblasts and the antigenic recombinant precursor on immunoblotting, but neither the fibroblast-derived mature enzyme nor the 64-kDa mature protein-like tryptic product of the recombinant precursor protein was immunoprecipitated. We conclude that it specifically recognized the precursor but not the mature protein in solution. Immunoprecipitation with this anti-precursor antibody revealed that the precursor protein mainly accounted for the residual enzyme activity in fibroblasts from an adult G M1 -gangliosidosis patient, and the mature protein accounted for the activity in fibroblasts from a juvenile G M1 -gangliosidosis patient.