Chang L M, Plevani P, Bollum F J
J Biol Chem. 1982 May 25;257(10):5700-6.
A high molecular weight preparation of terminal transferase containing 58,000- and 44,000-dalton peptides has been purified from calf thymus glands. The relationship of these terminal transferase peptides to the low molecular weight form was established with an immunoblot procedure using rabbit antibody directed against the homogeneous calf thymus low molecular weight terminal transferase (32,000 daltons). The 58,000- and 44,000-dalton enzyme species are each shown to be enzymatically active by renaturation in situ after electrophoresis on polyacrylamide gel in the presence of sodium dodecyl sulfate. These results suggest that the homogeneous terminal transferase previously described is derived from the higher molecular weight species by proteolysis during fractionation. Controlled degradation of the high molecular weight calf thymus terminal transferase with trypsin produces fully active enzyme containing alpha- and beta-peptides similar to those found in the 32,000-dalton species. Isoelectric focusing experiments show a decrease of isoelectric pH of the enzyme with proteolysis.
已从小牛胸腺中纯化出一种含有58,000道尔顿和44,000道尔顿肽的高分子量末端转移酶制剂。使用针对纯小牛胸腺低分子量末端转移酶（32,000道尔顿）的兔抗体，通过免疫印迹法确定了这些末端转移酶肽与低分子量形式的关系。在十二烷基硫酸钠存在下，经聚丙烯酰胺凝胶电泳后原位复性，结果表明58,000道尔顿和44,000道尔顿的酶种类均具有酶活性。这些结果表明，先前描述的纯末端转移酶是在分级分离过程中通过蛋白水解从较高分子量的种类衍生而来的。用胰蛋白酶对高分子量小牛胸腺末端转移酶进行可控降解，产生了含有与32,000道尔顿种类中发现的α-和β-肽相似的完全活性酶。等电聚焦实验表明，随着蛋白水解，该酶的等电pH值降低。
