Characterization of a ribonuclease gene and encoded protein from the reptile, Iguana iguana.
Characterization of a ribonuclease gene and encoded protein from the reptile, Iguana iguana.
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爬行动物鬣蜥核糖核酸酶基因和编码蛋白的表征。
DOI：
10.1016/j.gene.2005.03.002
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发表时间：
2005
期刊：
影响因子：
3.5
通讯作者：
Rosenberg,HeleneF
中科院分区：
文献类型：
--
作者：
Nitto,Takeaki;Lin,Cynthia;Dyer,KimberlyD;Wagner,RobertA;Rosenberg,HeleneF
在这项工作中，我们从鬣蜥IgH2细胞系的基因组DNA中鉴定出一个编码RNase A核糖核酸酶的无内含子开放阅读框。鬣蜥RNase主要在胰腺中表达，并代表了该组织中大多数特定的酶活性。编码的序列与已知的哺乳动物序列具有许多相同的特征，包括关键的His12， lys40和his114催化残基以及对酵母tRNA底物的高效水解活性（kcat/Km=6×104M−1s−1），尽管在降低的最佳pH （pH 6.0）下。虽然鬣蜥RNase的催化活性不会被人胎盘RI降低，但鬣蜥RNase即使在微摩尔浓度下也不具有杀菌作用，也不具有细胞毒性。系统发育分析表明，其氨基酸序列与Chelydra serpentina（鳄龟）中分离的胰腺核糖核酸酶有中等程度（46%）的相似性，尽管这些核糖核酸酶与哺乳动物物种中特征的胰腺核糖核酸酶之间没有特定的关系。为了确定RNase A基因超家族中的关系和谱系，需要对非哺乳动物脊椎动物物种的核糖核酸酶进行进一步分析。
In this work we identify an intronless open reading frame encoding an RNase A ribonuclease from genomic DNA from the Iguana iguana IgH2 cell line. The iguana RNase is expressed primarily in pancreas, and represents the majority of the specific enzymatic activity in this tissue. The encoded sequence shares many features with its better-known mammalian counterparts including the crucial His12, Lys40and His114catalytic residues and efficient hydrolytic activity against yeast tRNA substrate (kcat/Km=6×104M−1s−1), albeit at a reduced pH optimum (pH 6.0). Although the catalytic activity of the iguana RNase is not diminished by human placental RI, iguana RNase is not bactericidal nor is it cytotoxic even at micromolar concentrations. Phylogenetic analysis indicates moderate (46%) amino acid sequence similarity to a pancreatic RNase isolated from Chelydra serpentina (snapping turtle) although no specific relationship could be determined between these RNases and the pancreatic ribonucleases characterized among mammalian species. Further analysis of ribonucleases from non-mammalian vertebrate species is needed in order to define relationships and lineages within the larger RNase A gene superfamily.