Bradbeer M, Robinson J A, Robinson H C
Department of Biochemistry, Monash University, Clayton, Vic., Australia.
Biochem Int. 1990 Sep;21(6):1161-8.
Embryonic chicken cartilage was incubated in vitro with phenyl-beta-[6-3H]galactoside and cycloheximide. Free chondroitin sulphate chains initiated by galactoside were isolated and degraded to yield 3-O-beta-D-glucuronosyl D-galactose (GlcA-Gal) derived from the sequence, GlcA-Gal-Gal-Xyl-Ser, which links the polysaccharide to protein. This enabled the distribution of 3H into specific galactose residues within the linkage oligosaccharide to be determined. Most of the 3H label (65%) was released as free galactose although 35% was recovered as GlcA-Gal. Similar experiments performed with unlabelled phenyl-beta-galactoside and [14C]galactose yielded 14C-labelled GlcA-Gal as a major product. We conclude that beta-galactosides initiate chondroitin sulphate synthesis primarily by serving as substrates for galactosyl transferase II.
将鸡胚胎软骨在体外与苯基-β-[6-³H]半乳糖苷和环己酰亚胺一起孵育。分离出由半乳糖苷引发的游离硫酸软骨素链，并将其降解以产生源自GlcA-Gal-Gal-Xyl-Ser序列的3-O-β-D-葡萄糖醛酸基-D-半乳糖（GlcA-Gal），该序列将多糖与蛋白质相连。这使得能够确定³H在连接寡糖内特定半乳糖残基中的分布。尽管35%的³H以GlcA-Gal的形式回收，但大部分³H标记（65%）以游离半乳糖的形式释放。用未标记的苯基-β-半乳糖苷和[¹⁴C]半乳糖进行的类似实验产生了¹⁴C标记的GlcA-Gal作为主要产物。我们得出结论，β-半乳糖苷主要通过作为半乳糖基转移酶II的底物来启动硫酸软骨素的合成。
