Biochemical and atomic force microscopic characterization of salmon nasal cartilage proteoglycan

Biological activities of salmon nasal cartilage proteoglycan fractions are known, however, structural information is lacking. Recently, the major proteoglycan of this cartilage was identified as aggrecan. In this study, global molecular images and glycosaminoglycan structure of salmon nasal cartilage aggrecan purified from 4 M guanidine hydrochloride extract were analyzed using HPLCs and atomic force microscopy with bovine tracheal cartilage aggrecan as a control. The estimated numbers of sulfates per disaccharide unit of chondroitin sulfate chains of salmon and bovine aggrecans were similar (approximately 0.85). However, the disaccharide composition showed a higher proportion of chondroitin 6-sulfate units in salmon aggrecan, 60%, compared to 40% in bovine. Gel filtration HPLC and monosaccharide analysis showed the salmon aggrecan had a lower number (approximately one-third), but 1.5–3.3 times longer chondroitin sulfate chains than the bovine aggrecan. Atomic force microscopic molecular images of aggrecan supported the images predicted by biochemical analyses.