PROBLEM TO BE SOLVED: To provide a glycosynthase which can be used for remodeling of an antibody sugar chain, has broader substrate specificity than conventional enzymes, is an enzyme with a high specific activity, and exerts activity in broader pH ranges.SOLUTION: The present invention provides substrate specificity: efficiently transferring a sugar chain derived from a donor substrate to an acceptor substrate under conditions of pH 4 or more to 10 or less in a reaction system using as an acceptor substrate an antibody in which only N-acetyl glucosamine is bounded to "a glycosylation site which is present in the Fc region of an antibody" as a sugar chain component, or "an antibody in the state that α1,6-binding fucose is added to the N-acetyl glucosamine", the reaction system also using various sugar chains as donor substrates.SELECTED DRAWING: Figure 7【課題】抗体糖鎖のリモデリングに使用できるグライコシンターゼで、従来の酵素より基質特異性が広く、比活性の高い酵素であり、かつより広いｐＨ領域でも活性を示すグライコシンターゼを提供すること。【解決手段】基質特異性：糖鎖成分としてＮ－アセチルグルコサミンのみが「抗体のＦｃ領域に存在する糖鎖付加部位」に結合した抗体、または「そのＮ－アセチルグルコサミンにα１，６－結合したフコースが付加した状態の抗体」をアクセプター基質とし、各種糖鎖をドナー基質とした反応系において、ｐＨ４以上１０以下の条件下で、ドナー基質由来の糖鎖をアクセプター基質に効率よく糖鎖転移する。【選択図】図７
