Sugimoto Y, Yamada M
Biochem Cell Biol. 1986 Jun;64(6):543-7. doi: 10.1139/o86-076.
An enzyme which hydrolyzes benzoyl-L-tyrosine ethyl ester (BTEE) was purified from yolk sac membranes of day-18 chick embryos. The purified BTEE hydrolase has a molecular weight of 110,000, being composed of 70,000 and 40,000 subunits, and preferred synthetic substrates for chymotrypsin to those for trypsin. The optimum pH and temperature of this enzyme were 6.5-7.0 and 40 degrees C, respectively. The Km value for BTEE of the enzyme was 16 mM at pH 6.5 and 30 degrees C. The enzyme was inhibited markedly by some chymotrypsin inhibitors but scarcely inhibited by trypsin inhibitors. Magnesium ion acted as potent activator, depending on the enzyme purity and its concentration, whereas p-chloromercuribenzoate and zinc ion inactivated the activity markedly. The BTEE hydrolase was found to hydrolyze proteins such as casein and hemoglobin. These data indicated that the enzyme is a proteinase similar to chymotrypsin. This proteinase could act on yolk proteins, suggesting that it plays an important role in the metabolism of yolk at the yolk sac membrane layer.
从18日龄鸡胚的卵黄囊膜中纯化出一种可水解苯甲酰-L-酪氨酸乙酯（BTEE）的酶。纯化后的BTEE水解酶分子量为110,000，由70,000和40,000的亚基组成，相比于胰蛋白酶的底物，它更倾向于胰凝乳蛋白酶的合成底物。该酶的最适pH和温度分别为6.5 - 7.0和40℃。在pH 6.5和30℃条件下，该酶对BTEE的Km值为16 mM。该酶受到一些胰凝乳蛋白酶抑制剂的显著抑制，但几乎不受胰蛋白酶抑制剂的抑制。镁离子作为强效激活剂，这取决于酶的纯度及其浓度，而对氯汞苯甲酸和锌离子则显著使该酶失活。发现BTEE水解酶可水解诸如酪蛋白和血红蛋白等蛋白质。这些数据表明该酶是一种类似于胰凝乳蛋白酶的蛋白酶。这种蛋白酶可作用于卵黄蛋白，表明它在卵黄囊膜层的卵黄代谢中起重要作用。
