Takagaki K, Nakamura T, Majima M, Endo M
Department of Biochemistry, Hirosaki University School of Medicine, Japan.
J Biol Chem. 1988 May 25;263(15):7000-6.
An endo-beta-glucuronidase acting on chondroitin sulfate was isolated from rabbit liver and purified about 550-fold, using a combination of ammonium sulfate fractionation, DEAE-cellulose chromatography, gel filtration on Sephacryl S-300, affinity chromatography through heparin-Sepharose CL-6B and preparative polyacrylamide gel electrophoresis. The pH optimum of this enzyme was 4.0 and the Km value 7 X 10(-3) M for chondroitin sulfate (Mr 40,000). The isoelectric point of the enzyme was found to be at pH 5.4. The molecular weight, estimated by gel filtration through Sephacryl S-200 and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was 35,000. This enzyme, which was found in the liver, kidney, spleen, and lung, hydrolyzed the glucuronyl galactose linkage of the linkage region of chondroitin sulfate possessing a very small peptide segment. The enzyme did not hydrolyze proteoglycan. It was concluded that an endo-beta-glucuronidase is involved in the catabolism of proteoglycan chondroitin sulfates.
从兔肝脏中分离出一种作用于硫酸软骨素的内切β-葡萄糖醛酸酶，并通过硫酸铵分级分离、DEAE-纤维素色谱法、Sephacryl S-300凝胶过滤、肝素-琼脂糖CL-6B亲和色谱法和制备性聚丙烯酰胺凝胶电泳等方法组合将其纯化了约550倍。该酶的最适pH值为4.0，对硫酸软骨素（分子量40,000）的Km值为7×10⁻³ M。发现该酶的等电点为pH 5.4。通过Sephacryl S-200凝胶过滤和十二烷基硫酸钠-聚丙烯酰胺凝胶电泳估计其分子量为35,000。这种在肝脏、肾脏、脾脏和肺中发现的酶，水解了具有非常小的肽段的硫酸软骨素连接区的葡萄糖醛酸基半乳糖键。该酶不水解蛋白聚糖。得出的结论是，一种内切β-葡萄糖醛酸酶参与了蛋白聚糖硫酸软骨素的分解代谢。
