CHSY1 transfers GalNAc to chondroitin

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.

N-乙酰半乳糖胺（GalNAc）基团通过双功能酶——软骨素硫酸酯合酶1-3（分别简称为CHSY1、CHPF和CHSY3）（Kitagawa等，2001年，Yada等，2003年，Yada等，2003年b）——被添加到软骨素链中。这些酶同时具备β-1,3-葡萄糖醛酸和β-1,4-N-乙酰半乳糖胺转移酶的活性，后者活性在此反应中被利用。这三种酶作为辅因子需要二价金属离子，其中锰能够产生最高的活性。GlcA-GalNAc重复的二糖单元将此糖胺聚糖识别为软骨素。