论文标题
两态蛋白酰基磷酸酶的自由能景观具有较大的接触顺序，由力依赖性折叠和展开动力学揭示
Free energy landscape of two-state protein Acylphosphatase with large contact order revealed by force-dependent folding and unfolding dynamics
论文作者
论文摘要
酰基磷酸酶（ACP）是一种具有98个氨基酸残基的小蛋白，可催化羧基磷酸键的水解。 ACP是一种典型的两态蛋白质，由于天然结构中的接触率相对较大，其折叠率较慢。原子力显微镜已经研究了ACP的机械性能和展开行为。但是尚未报道低力的折叠和展开动力。在这里，使用稳定的磁镊子，我们测量了力依赖性折叠速率在1 pn到3 pn的范围内，并将速率从15 pn到40 pn。所获得的展开速率显示出在〜27 pn下方和以上的力的力敏感性不同，这决定了具有两个能屏障的自由能景观。我们的结果表明，小球蛋白的自由能景观具有一般的Bactrian骆驼形状，而天然状态的较大接触顺序在低力下会产生高屏障。
Acylphosphatase (AcP) is a small protein with 98 amino acid residues that catalyzes the hydrolysis of carboxyl-phosphate bonds. AcP is a typical two-state protein with slow folding rate due to its relatively large contact order in the native structure. The mechanical properties and unfolding behavior of AcP has been studied by atomic force microscope. But the folding and unfolding dynamics at low forces has not been reported. Here using stable magnetic tweezers, we measured the force-dependent folding rates within a force range from 1 pN to 3 pN, and unfolding rates from 15 pN to 40 pN. The obtained unfolding rates show different force sensitivities at forces below and above ~27 pN, which determines a free energy landscape with two energy barriers. Our results indicate that the free energy landscape of small globule proteins have general Bactrian camel shape, and large contact order of the native state produces a high barrier dominate at low forces.
