The present disclosure relates to glycoproteins, particularly monoclonal antibodies, comprising a glycoengineered Fc region, wherein said Fc region comprises an optimized N-glycan having the structure of Sia2(α2-6)Gal2GlcNAc2Man3GlcNAc2. The glycoengineered Fc region binds FcγRIIA or FcγRIIIA with a greater affinity, relative to comparable monoclonal antibodies comprising the wild-type Fc region. The monoclonal antibodies of the invention are particularly useful in preventing, treating, or ameliorating one or more symptoms associated with a disease, disorder, or infection where an enhanced efficacy of effector cell function (e.g., ADCC) mediated by FcγR is desired, e.g., cancer, autoimmune, infectious disease, and in enhancing the therapeutic efficacy of therapeutic antibodies the effect of which is mediated by ADCC.