Coleman, D.J., Kuntz, D.A., Venkatesan, M., Cook, G.M., Williamson, S.P., Rose, D.R., Naleway, J.J. (2010). A long-wavelength fluorescent substrate for continuous fluorometric determination of alpha-mannosidase activity: Resorufin alpha-d-mannopyranoside.  Anal. Biochem. 399(1): 7--12.

FBrf0210065

Research paper

A simple and reliable continuous assay for measurement of alpha-mannosidase activity is described and demonstrated for analysis with two recombinant human enzymes using the new substrate resorufin alpha-d-mannopyranoside (Res-Man). The product of enzyme reaction, resorufin, exhibits fluorescence emission at 585 nm with excitation at 571 nm and has a pK(a) of 5.8, allowing continuous measurement of fluorescence turnover at or near physiological pH values for human lysosomal and Drosophila Golgi alpha-mannosidases. The assay performed using recombinant Drosophila Golgi alpha-mannosidase (dGMII) has been shown to give the kinetic parameters K(m) of 200 microM and V(max) of 11 nmol/min per nmol dGMII. Methods for performing the assay using several concentrations of the known alpha-mannosidase inhibitor swainsonine are also presented, demonstrating a potential for use of the assay as a simple method for high-throughput screening of inhibitors potentially useful in cancer treatment.

PMC2824011 (PMC) (EuropePMC)