A third beta-glucosidase from human liver has been isolated using a mild (0.02-0.10%) Triton X-100 extraction of the exhaustively washed high speed (200,000 X g, 30 min) particulate fraction, QAE-Sephadex and concanavalin A-Sepharose chromatography. This new beta-glucosidase, referred to as TX beta-glucosidase, possesses a distinctive set of chemical properties such that it is similar to both, glucocerebrosidase and cytoplasmic beta-glucosidase, but it is not identical to either enzyme. 2. The TX beta-glucosidase hydrolyzes glucocerebroside as well as the beta-D-glucose, beta-D-galactose, beta-D-fucose, beta-D-xylose and alpha-L-arabinose derivatives of 4-methylumbelliferone. Like the cytoplasmic beta-glucosidase, the TX beta-glucosidase is inhibited by bile salts, and unaffected by conduritol B epoxide and heat stable activator protein. 3. All three beta-glucosidases were inhibited by N-hexylpsychosine, and all showed the same, mixed type inhibition kinetics, indicating a common hydrophobic binding site in all three enzymes. 4. The TX beta-glucosidase, which constitutes only a few percent of the total beta-glucosidase activity of human liver, is absent from liver from two cases of neurologic Gaucher disease and present in reduced amounts in a third case with CNS disease. Liver from a case of type 1 Gaucher disease contained normal amounts of the TX beta-glucosidase.
摘要
利用温和的（0.02 - 0.10%） Triton X - 100对经充分洗涤的高速（200,000×g，30分钟）微粒部分进行提取，再通过QAE - 葡聚糖凝胶和伴刀豆球蛋白A - 琼脂糖凝胶色谱法，从人肝脏中分离出了第三种β - 葡萄糖苷酶。这种新的β - 葡萄糖苷酶，称为TXβ - 葡萄糖苷酶，具有一系列独特的化学性质，使其既类似于葡糖脑苷脂酶，又类似于细胞质β - 葡萄糖苷酶，但与这两种酶都不完全相同。2. TXβ - 葡萄糖苷酶能水解葡糖脑苷脂以及4 - 甲基伞形酮的β - D - 葡萄糖、β - D - 半乳糖、β - D - 岩藻糖、β - D - 木糖和α - L - 阿拉伯糖衍生物。与细胞质β - 葡萄糖苷酶一样，TXβ - 葡萄糖苷酶受胆汁盐抑制，不受制霉菌醇B环氧化物和热稳定激活蛋白影响。3. 所有三种β - 葡萄糖苷酶都被N - 己基神经鞘氨醇抑制，并且都表现出相同的混合型抑制动力学，表明这三种酶中存在一个共同的疏水结合位点。4. TXβ - 葡萄糖苷酶仅占人肝脏总β - 葡萄糖苷酶活性的百分之几，在两例神经型戈谢病患者的肝脏中不存在，而在第三例患有中枢神经系统疾病的患者肝脏中含量减少。1型戈谢病患者的肝脏中TXβ - 葡萄糖苷酶含量正常。
