Purification and characterization of pepsins A1 and A2 from the Antarctic rock cod Trematomus bernacchii
Purification and characterization of pepsins A1 and A2 from the Antarctic rock cod Trematomus bernacchii
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DOI：
10.1111/j.1742-4658.2007.06136.x
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发表时间：
2007-12-01
期刊：
影响因子：
5.4
通讯作者：
Engen, John R.
中科院分区：
文献类型：
--
作者：
Brier, Sebastien;Maria, Giovanna;Engen, John R.
南极鳕鱼（岩鳕）生活在零下 1.9 摄氏度的恒定平均温度下。在这种条件下，胃消化依赖于胃蛋白酶等天冬氨酸蛋白酶的蛋白水解活性。为了了解南极鱼类胃蛋白酶的分子机制，对 T. bernacchii 胃蛋白酶 A1 和 A2 进行了克隆，在大肠杆菌中过表达，并通过多种生化和生物物理方法进行纯化和表征。将这两种南极同工酶的特性与猪胃蛋白酶的特性进行比较，发现它们在许多方面都是独特的。研究发现，鱼胃蛋白酶对温度更敏感，通常在较低 pH 下活性较低，并且与嗜温对应物相比，对胃酶抑素的抑制更敏感。南极鱼胃蛋白酶的特异性与猪胃蛋白酶相似但不完全相同，这可能是由于活性位点附近的鱼酶序列发生了变化。南极岩鳕鱼胃蛋白酶的基因复制可能是适应这些酶必须发挥作用的恶劣温度环境的机制。
The Antarctic notothenioid Trematomus bernacchii (rock cod) lives at a constant mean temperature of - 1.9 degrees C. Gastric digestion under these conditions relies on the proteolytic activity of aspartic proteases such as pepsin. To understand the molecular mechanisms of Antarctic fish pepsins, T. bernacchii pepsins A1 and A2 were cloned, overexpressed in Escherichia coli, purified and characterized with a number of biochemical and biophysical methods. The properties of these two Antarctic isoenzymes were compared to those of porcine pepsin and found to be unique in a number of ways. Fish pepsins were found to be more temperature sensitive, generally less active at lower pH and more sensitive to inhibition by pepstatin than their mesophilic counterparts. The specificity of Antarctic fish pepsins was similar but not identical to that of pig pepsin, probably owing to changes in the sequence of fish enzymes near the active site. Gene duplication of Antarctic rock cod pepsins is the likely mechanism for adaptation to the harsh temperature environment in which these enzymes must function.