Chelator-Conjugated Substrates for N-Acetyl-β-D-Glucosaminidase

Abstract

Compounds in which N-acetyl-D-glucosaminide groups were covalently attached to chromogenic metal chelators at their metal-binding sites were synthesized as substrates for N-acetyl-β-D-glucosaminidase (NAGase). Upon incubation with NAGase in the presence of Fe(III), Cu(II) or Co(II) at pH 4.5-5.1, these substrates gave an absorbance increase corresponding to respective metal complexes of their aglycons. Although this approach permitted the rate-assay of
NAGase under the conditions of weakly acidic pH (which had not yet been reported), problems using the chelator-conjugated substrates are tend to be hydrolytic instabilities of the substrates and inhibitory effect of the metal ions over the enzyme.