Eukaryotic recombinant proteins expressed in bacterial cells usually aggregate within the cells as inclusion bodies. Despite the widely-accepted theory considering inclusion bodies as inactive materials, inclusion bodies may contain large amounts of correctly-folded active recombinant proteins. Proteins trapped in inclusion bodies can be released using a high pH solution (pH ≥ 11); however, they may undergo structural changes in such pH conditions that may lead to their inactivation. Shifting in pH alongside the use of metal ions can help recover protein activity. The model protein we used in this study, 9R-Nimo.scFv, is highly active when extracted from bacterial inclusion bodies at high pH condition (pH 12) but loses its activity when pH is reduced to pH 7. We evaluated the capacity of nine salt solutions in terms of recovering protein activity in neutral pH conditions and found that ZnSO4 solution was the best one for this purpose. KNO3 and MnSO4 were also found to have a good capacity for recovering protein activity, as well.

中文翻译：

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在中性pH条件下，使用盐溶液从细菌包涵体中获得活性重组蛋白。

在细菌细胞中表达的真核重组蛋白通常在细胞内聚集为包涵体。尽管广泛接受的理论将包涵体视为非活性材料，但包涵体可能包含大量正确折叠的活性重组蛋白。可以使用高pH溶液（pH≥11）释放包涵体中捕获的蛋白质。但是，它们可能会在这种pH条件下发生结构变化，从而导致其失活。pH值的变化以及金属离子的使用可以帮助恢复蛋白质活性。我们在这项研究中使用的模型蛋白9R-Nimo.scFv在高pH条件（pH 12）下从细菌包涵体中提取时具有很高的活性，但在pH降低至pH 7时会失去活性。我们评估了九种盐溶液在中性pH条件下恢复蛋白质活性方面的能力，并发现ZnSO4溶液是用于此目的的最佳盐溶液。还发现KNO 3和MnSO 4也具有恢复蛋白质活性的良好能力。