β-D-GlcpNAc-(1→4)-β-D-GlcpA-(1→3)-β-D-GlcpNAc-(1→4)-β-D-GlcpA-(1→3)-β-D-GlcpNAc-(1→4)-β-D-GlcpA-(1→3)-β-D-GlcpNAc-(1→4)-?-D-Glc?A-(1→