Zhao W, Beintema J J, Hofsteenge J
Biochemisch Laboratorium, Rijksuniversiteit, Groningen.
Eur J Biochem. 1994 Jan 15;219(1-2):641-6. doi: 10.1111/j.1432-1033.1994.tb19979.x.
The pyrimidine-specific ribonuclease superfamily constitutes a group of homologous proteins so far found only in higher vertebrates. Four separate families are found in mammals, which have resulted from gene duplications in mammalian ancestors. To learn more about the evolutionary history of this superfamily, the primary structure and other characteristics of the pancreatic enzyme from iguana (Iguana iguana), a herbivorous lizard species belonging to the reptiles, have been determined. The polypeptide chain consists of 119 amino acid residues. The positions of insertions and deletions in the sequence are identical to those in the enzyme from snapping turtle. However, the two enzymes differ at 54% of the amino acid positions. Iguana ribonuclease contains no carbohydrate, although the enzyme possesses three recognition sites for carbohydrate attachment, and has a high number of acidic residues in a localized part of the sequence.
嘧啶特异性核糖核酸酶超家族由一组目前仅在高等脊椎动物中发现的同源蛋白组成。在哺乳动物中发现了四个不同的家族，它们是由哺乳动物祖先中的基因复制产生的。为了更多地了解这个超家族的进化历史，已经确定了来自鬣蜥（Iguana iguana）的胰腺酶的一级结构和其他特征，鬣蜥是一种属于爬行动物的食草蜥蜴物种。多肽链由119个氨基酸残基组成。序列中插入和缺失的位置与鳄龟酶中的相同。然而，这两种酶在54%的氨基酸位置上存在差异。鬣蜥核糖核酸酶不含碳水化合物，尽管该酶具有三个碳水化合物附着识别位点，并且在序列的局部区域有大量酸性残基。
