Silbert J E
J Biol Chem. 1978 Oct 10;253(19):6888-92.
Incubation of chick embryo epiphyseal microsomal preparations with either UDP-[14C]GlcUA or UDP-[14C]-GalNAc plus exogenous chondroitin 6-sulfate resulted in the incorporation of either a single [14C]GlcUA or a [14C]GalNAc onto the nonreducing ends of the exogenous glycosaminoglycan. Degradation by chondroitinase ABC yielded the terminal products [14C]Di-OS, [14C]Di-6S, and [14C]GalNAc. Incubations of the microsomal preparations with either UDP-[14C]GlcUA or UDP-GalN[3H]Ac without exogenous chondroitin 6-sulfate resulted in the addition of a single sugar onto the nonreducing end of endogenous chondroitin sulfate. Degradation by chondroitinase ABC yielded the terminal products [14C]Di-OS, [14C]Di-6S, and GalN[3H]Ac in a molar ratio of approximately 1:1:3.5. Incubations of the microsomal preparations with both UDP-[14C]-GlcUA and UDP-GalN[3H]Ac together resulted in formation of [14C,3H]chondroitin chains added to the endogenous chondroitin sulfate. Degradation by chondroitinase ABC resulted in products with a molar ratio of [14C,3H]Di-OS to GalN[3H]Ac varying from approximately 1:1.5 to 1:3. The results of these experiments indicate that chondroitin 6-sulfate terminates at its nonreducing end in a mixture of GlcUA and GalNAc (some sulfated). GalNAc is somewhat more frequent as the terminal sugar and adds more readily to endogenous acceptors.
用UDP-[14C]葡萄糖醛酸（UDP-[14C]GlcUA）或UDP-[14C] -N-乙酰半乳糖胺（UDP-[14C]-GalNAc）加上外源性硫酸软骨素6-硫酸酯孵育鸡胚骨骺微粒体制剂，会导致单个[14C]葡萄糖醛酸或[14C] -N-乙酰半乳糖胺掺入外源性糖胺聚糖的非还原末端。用软骨素酶ABC降解产生终产物[14C]二糖硫酸酯（[14C]Di-OS）、[14C]二糖6-硫酸酯（[14C]Di-6S）和[14C] -N-乙酰半乳糖胺。在没有外源性硫酸软骨素6-硫酸酯的情况下，用UDP-[14C]葡萄糖醛酸或UDP-[3H] -N-乙酰半乳糖胺（UDP-GalN[3H]Ac）孵育微粒体制剂，会导致在内源性硫酸软骨素的非还原末端添加单个糖。用软骨素酶ABC降解产生终产物[14C]二糖硫酸酯、[14C]二糖6-硫酸酯和[3H] -N-乙酰半乳糖胺，其摩尔比约为1:1:3.5。同时用UDP-[14C]葡萄糖醛酸和UDP-[3H] -N-乙酰半乳糖胺孵育微粒体制剂会导致形成添加到内源性硫酸软骨素上的[14C,3H]硫酸软骨素链。用软骨素酶ABC降解产生的产物中，[14C,3H]二糖硫酸酯与[3H] -N-乙酰半乳糖胺的摩尔比在约1:1.5至1:3之间变化。这些实验结果表明，硫酸软骨素6-硫酸酯在其非还原末端以葡萄糖醛酸和N-乙酰半乳糖胺（一些硫酸化）的混合物终止。N-乙酰半乳糖胺作为末端糖出现的频率略高，并且更容易添加到内源性受体上。
