Self-association of human beta-galactocerebrosidase: Dependence on pH, salt, and surfactant

Krabbe disease, also known as globoid cell leukodystrophy, is a rare genetic neurodegenerative disease caused by a deficiency of the galactocerebrosidase enzyme. To understand the association status of human beta-galactocerebrosidase (hGALC) in solution, we employed analytical ultracentrifugation (AUC). Our AUC results show that hGALC has a tendency for reversible self-association. Self-association decreases as the concentration of sodium chloride increases from 50 to 500 mM. This indicates that ionic interactions are involved in the association. The association is also dependent on pH, and high order oligomerization decreases as the pH increases from 4.5 to 7.5. Taken together, our results indicate that hGALC has the highest tendency for oligomerization at physiological ionic strength and pH (lysosomal lumen). This is the first report describing the self-associating property of hGALC in solution.