Enzymatic extension of A) core M1 and B) core M2 structures. Reagents and conditions: a) NmLgtB, UDP-Gal, Mg2+; b) PmST1-M144D, NmCSS, Neu5Ac, CTP, Mg2+; c) Pd26ST, NmCSS, Neu5Ac, CTP, Mg2+; d) Hp3FT, GDP-Fuc, Mg2+; e) PmST1-M144D, NmCSS, Neu5Gc, CTP, Mg2+; f) Pd26ST, NmCSS, Neu5Gc, CTP, Mg2+; g) GlcAT-P, UDP-GlcA, Mg2+; h) PmST1m, NmCSS, Neu5Ac, CTP, Mg2+; i) βGalD.