An N-acetylgalactosamine (GalNAc) moiety is added to the chondroitin chain by dual-activity enzymes, the chondroitin sulfate synthases 1-3 (CHSY1, CHPF and CHSY3 respectively) (Kitagawa et al. 2001, Yada et al. 2003, Yada et al. 2003b). They possess both beta-1,3-glucuronic acid and beta-1,4-N-acetylgalactosamine transferase activity, the latter activity used in this reaction. These three enzymes require divalent metals as cofactors, manganese producing the highest activities. The repeated disaccharide units of GlcA-GalNAc identify this glycosaminoglycan as chondroitin.
Yada, T, Gotoh, M, Sato, T, Shionyu, M, Go, M, Kaseyama, H, Iwasaki, H, Kikuchi, N, Kwon, YD, Togayachi, A, Kudo, T, Watanabe, H, Narimatsu, H, Kimata, K
Kitagawa, H, Uyama, T, Sugahara, K
Yada, T, Sato, T, Kaseyama, H, Gotoh, M, Iwasaki, H, Kikuchi, N, Kwon, YD, Togayachi, A, Kudo, T, Watanabe, H, Narimatsu, H, Kimata, K
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