A new resorufin-based α-glucosidase assay for high-throughput screening

Abstract

Mutations in α-glucosidase cause accumulation of glycogen in lysosomes, resulting in Pompe disease, a lysosomal storage disorder. Small molecule chaperones that bind to enzyme proteins and correct the misfolding and mistrafficking of mutant proteins have emerged as a new therapeutic approach for the lysosomal storage disorders. In addition, α-glucosidase is a therapeutic target for type II diabetes, and α-glucosidase inhibitors have been used in the clinic as alternative treatments for this disease. We have developed a new fluorogenic substrate for the α-glucosidase enzyme assay, resorufin α- d-glucopyranoside. The enzyme reaction product of this new substrate emits at a peak of 590 nm, reducing the interference from fluorescent compounds seen with the existing fluorogenic substrate, 4-methylumbelliferyl-α- d-glucopyranoside. Also, the enzyme kinetic assay can be carried out continuously without the addition of stop solution due to the lower p K a of the product of this substrate. Therefore, this new fluorogenic substrate is a useful tool for the α-glucosidase enzyme assay and will facilitate compound screening for the development of new therapies for Pompe disease.