3-O-{beta-D-Xyl-(1->3)-[beta-D-Gal-(1->2)]-beta-D-GlcA}-quillate + UDP-4-dehydro-6-deoxy-alpha-D-glucose = 3-O-{beta-D-Xyl-(1->3)-[beta-D-Gal-(1->2)]-beta-D-GlcA}-quillaic acid 4-dehydro-6-deoxy-beta-D-Glc ester + UDP — reaction