A method of purifying sialidase-L from M. decora consisting of the steps of preparation of a concentrated crude enzyme preparation and sequential chromatography of the crude enzyme preparation using columns packed with Fractogel TSK DEAE-650(M), octyl CL-4b, Fractogel EMD SO.sub.3 -650(M), Sephadex G-100, Matrex Blue A and Hypatite C, and recovering the purified sialidase-L enzyme, wherein the purified enzyme has a molecular weight of 84,000 daltons when analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoreses and an optimal pH of between pH 5.5 and 6.0, the purified enzyme being unstable in 50 mM sodium acetate buffer at pH 5.5 and stable for at least three months when stored at -35.degree. C. in the presence of 10% glycerol and where the enzyme is capable of synthesizing 2,7-anhydro-N-acetylneuraminic acid.