Kinetic and biophysical characterization of a lysosomal α-l-fucosidase from the fresh water mussel, Lamellidens corrianus

Abstract Kinetic and biophysical studies have been carried out on a lysosomal α- l -fucosidase purified from the fresh water mussel, Lamellidens corrianus. The enzyme migrates as a single band in SDS-PAGE as well as native PAGE corresponding to a M r of 56 kDa. Mass spectrometric analysis yielded a molecular mass of 56175.1 Da for the enzyme, and peptide mass fingerprinting studies showed that it shares sequence homology with other fucosidases. Zymogram analysis showed that the α- l -fucosidase hydrolyzed 4-methyl umbelliferyl α- l -fucopyranoside. The pH and temperature optima of the enzyme were found to be 5.0–6.0 and 60 °C, respectively. The K M , V max and k cat values of the enzyme estimated with p -nitrophenyl fucopyranoside are 0.85 mM, 27.20 mU/mL and 1.01 s −1 , respectively. The inhibition constant (K i ) of the enzyme towards l -Fucose is 1.09 mM. CD spectral analysis has shown that the protein contains predominantly β-sheets in its secondary structure. Chemical unfolding studies indicate that α- l -fucosidase unfolds in a broad sigmoidal, cooperative unfolding transition, centered at ∼2.2 M for both guanidinium chloride and guanidinium thiocyanate. The present results obtained with the L. corrianus α- l -fucosidase are expected to provide further insights into the various biological processes associated with fucosidases and help in exploiting this enzyme in therapeutic applications.