O-antigen group O:63 polymerase yielding a long O antigen chain length (25 repeat units)
25.0 udcdpgalnac_a1_3_galnac_a1_4_glc_b1_4_gal_a1_4_fuc3nac_p ⇌ 24.0 udcpdp_p + OA63__L_p