The results presented here demonstrate the potential applicability of the described cross-linking method for preparation of soluble glycoenzyme derivatives. The high level of the retained enzyme activity supports the assumption that this approach is superior to the cross-linking through the protein part. In this study, high mannose-type glycoproteins were used. However, the complex-type glycoproteins that are spread among glycoproteins of higher eukaryotes also can be cross-linked by this procedure because, at the least, the terminal monosaccharide will be oxidized by periodate. Moreover, this approach may be applicable when dealing with partially purified glycoenzymes because the protein impurities are not expected to interfere with the cross-linking reaction. Besides cross-linking, other kinds of chemical modifications of glycoenzymes through the carbohydrate part are possible. This, in turn, could lead to changes in the physicochemical and catalytic properties of the enzymes, thereby opening a new field of glycoenzyme engineering.