Lipoldová M, Cerná J, Takác M, Zadrazil S, Rychlík I
Folia Biol (Praha). 1985;31(2):71-80.
Poly(A) RNA from the mucosa of the fundal region of the fourth stomach of suckling calf and adult cattle was isolated by the phenol or guanidine thiocyanate procedure. The mRNAs for chymosin and pepsin were present in the 15S fraction of poly(A) RNA. They were active both in cell-free translation systems and in oocytes of Xenopus laevis and directed the synthesis of either chymosin or pepsin precursor, depending upon the age of the donor animal. In the reticulocyte and wheat germ system only preprochymosin or prepepsinogen were synthesized. In the oocyte system only the synthesis and secretion of prochymosin or pepsinogen could be detected. Both proenzymes, prochymosin and pepsinogen, present in oocytes or secreted into the medium, were converted to active enzymes, chymosin and pepsin, respectively, at pH 3.0, as shown by their proteolytic and milk-clotting activity.
通过苯酚或硫氰酸胍法从哺乳小牛和成年牛第四胃底部区域的黏膜中分离出多聚腺苷酸（Poly(A)）RNA。凝乳酶和胃蛋白酶的信使核糖核酸（mRNA）存在于Poly(A) RNA的15S组分中。它们在无细胞翻译系统以及非洲爪蟾卵母细胞中均具有活性，并根据供体动物的年龄指导凝乳酶或胃蛋白酶前体的合成。在网织红细胞和小麦胚芽系统中，仅合成前凝乳酶原或胃蛋白酶原。在卵母细胞系统中，仅能检测到前凝乳酶或胃蛋白酶原的合成与分泌。卵母细胞中存在的或分泌到培养基中的两种酶原，即前凝乳酶和胃蛋白酶原，在pH 3.0时分别转化为活性酶，即凝乳酶和胃蛋白酶，这可通过它们的蛋白水解活性和凝乳活性得以证明。
