[4)-beta-D-GlcpNAc-(1->4)-beta-?-Murp-(1->4)-beta-D-GlcpNAc-(1->4)-beta-?-Murp-(1->4)-beta-D-GlcpNAc-(1->4)-beta-?-Murp-(1->4)-beta-D-GlcpNAc-(1->4)-beta-?-MurpNAc-(1->]