Bowers W E, Panagides J, Yago N
Adv Exp Med Biol. 1977;95:301-12. doi: 10.1007/978-1-4757-0719-9_18.
Cathepsin D, an enzyme consistently found to be lysosomal in many cells, has an unusual localization in rat thoracic duct lymphocytes (TDL). After fractionation of homogenates of rat TDL, most of the enzyme activity, as measured at pH 3.6 on denatured bovine hemoglobin, is distributed differently from the other lysosomal enzymes. The enzyme also has some unique properties: it is not inhibited by an antiserum inhibitory for rat liver cathepsin D; it exists in two molecular weight forms (approximately 45,000 and approximately 95,000) both of which have a higher specific activity than rat liver cathepsin D, as determined by studies using the irreversible inhibitor, sodium pepstatin; the high molecular weight form converts to the low molecular weight form after treatment with beta-mercaptoethanol without any loss in activity. These enzymes appear to be restricted to rodent lymphoid tissues. Reasons for considering them to be a type of cathepsin D are given in the text.
组织蛋白酶D是一种在许多细胞中一直被发现存在于溶酶体的酶，但它在大鼠胸导管淋巴细胞（TDL）中却有不同寻常的定位。在对大鼠TDL匀浆进行分级分离后，以变性牛血红蛋白在pH 3.6条件下测定，大部分酶活性的分布与其他溶酶体酶不同。该酶还具有一些独特性质：它不受抑制大鼠肝脏组织蛋白酶D的抗血清的抑制；它以两种分子量形式存在（约45,000和约95,000），通过使用不可逆抑制剂胃蛋白酶抑制剂钠的研究确定，这两种形式的比活性均高于大鼠肝脏组织蛋白酶D；高分子量形式在用β-巯基乙醇处理后转化为低分子量形式，且活性没有任何损失。这些酶似乎局限于啮齿动物淋巴组织。文中给出了将它们视为一种组织蛋白酶D的原因。
