alpha-D-GlcpN2,6S23,4Suc2-(1->4)-alpha-L-IdopA2S-(1->4)-[4)-alpha-D-GlcpN2,6S23Suc-(1->4)-alpha-L-IdopA2S3Suc-(1->]n-alpha-D-GlcpN2,6S23Suc(1->