Young E, Horner A A
Biochem J. 1979 Jun 15;180(3):587-96. doi: 10.1042/bj1800587.
Homogenates of rat small intestine can depolymerize macromolecular rat skin heparin (RS heparin) to products similar in size to commercial heparin [Horner (1972) Proc. Natl. Acad. Sci. U.S.A. 69, 3469--3473]. This activity is attributed to an enzyme provisionally named 'macromolecular heparin depolymerase'. An assay for macromolecular heparin depolymerase activity in rat small intestine has been developed, based on the action of the enzyme on 35S-labelled macromolecular RS heparin. The depolymerized products are separated into two peaks by gel chromatography through columns of Bio-Gel A-15m. The amount of label in the second peak, expressed as a percentage of the total radioactivity, is the index of enzyme activity. The pH optimum was found to be 6.0 and the temperature optimum 45 degrees C. The enzyme was shown to be most stable in 50mM-Tris/maleate buffer containing 1 mM-EDTA. Macromolecular heparin depolymerase activity measured as a function of time and substrate concentration produced curves typical of an enzymic reaction. Evidence was obtained demonstrating that the activity did not originate from bacteria in the intestine. Macromolecular heparin depolymerase activity was increased by dilution and storage at 7 degrees C for 24 h. This suggests that homogenates of rat small intestine contain an unstable inhibitor of the enzyme.
大鼠小肠匀浆可将大鼠皮肤大分子肝素（RS肝素）解聚为大小与商业肝素相似的产物[霍纳（1972年）《美国国家科学院院刊》69, 3469 - 3473]。这种活性归因于一种暂名为“大分子肝素解聚酶”的酶。基于该酶对35S标记的大分子RS肝素的作用，已开发出一种测定大鼠小肠中大分子肝素解聚酶活性的方法。通过Bio - Gel A - 15m柱进行凝胶色谱法将解聚产物分离为两个峰。第二个峰中的标记量占总放射性的百分比即为酶活性指标。发现最适pH为6.0，最适温度为45℃。该酶在含有1 mM - EDTA的50mM - Tris/马来酸缓冲液中显示出最稳定。以时间和底物浓度为函数测定的大分子肝素解聚酶活性产生了典型的酶促反应曲线。已获得证据表明该活性并非源自肠道中的细菌。大分子肝素解聚酶活性经稀释并在7℃保存24小时后增加。这表明大鼠小肠匀浆中含有该酶的一种不稳定抑制剂。
