alpha-Neu5Ac-(2->3)-beta-D-Gal-(1->3)-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-D-Glc + CMP-N-acetyl-beta-neuraminate = alpha-Neu5Ac-(2->3)-beta-D-Gal-(1->3)-[alpha-Neu5Ac-(2->6)]-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-D-Glc + CMP + H(+) — reaction