Substrate inhibition of lysosomal hydrolases: α-Galactosidase A and β-glucocerebrosidase.

Objective: We have investigated the kinetics of α-galactosidase A and β-glucocerebrosidase deficient in Fabry and Gaucher diseases, respectively.

Design And Methods: We have performed spectrofluorymetric measurements of the activity of enzymes using a derivative of 4-methylumbelliferone as a substrate and a human T-cell line as a source of enzymes.

Results: We have observed the substrate inhibition effect, which is related to temperature.

Conclusions: The diagnostic procedures for Fabry and Gaucher diseases used now in laboratory practice neglect temperature-dependent substrate inhibition, which may significantly reduce the sensitivity of enzyme activity determinations.