Modulating Enzyme Catalysis through Mutations Designed to Alter Rapid Protein Dynamics.
Modulating Enzyme Catalysis through Mutations Designed to Alter Rapid Protein Dynamics.
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DOI：
10.1021/jacs.5b12551
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发表时间：
2016-03-16
影响因子：
15
通讯作者：
Schwartz SD
中科院分区：
文献类型：
--
作者：
Zoi I;Suarez J;Antoniou D;Cameron SA;Schramm VL;Schwartz SD
亚皮秒蛋白质运动与催化事件的相关性仍然是一个争论的话题。重酶（同位素取代的）为酶催化的键振动连接提供了实验工具。最近的一项使用重嘌呤核苷磷酸化酶（PNP）的过渡路径取样研究表征了实验观察到的屏障穿越的质量依赖性减慢（Antoniou，D.; Ge，X.; Schramm，V. L.;施瓦茨，S。D.《物理化学杂志》2012，3，3538）。在这里，我们计算确定第二球氨基酸残基预测影响的自由度的催化位点的振动模式连接到重酶的PNP的影响。我们突变了重和轻PNP以增加催化位点的振动自由度。酶的屏障穿越率从质量依赖转换为质量无关的突变的结果。催化位点群和反应物之间的飞秒运动的诱变解偶联减少了2个数量级的过渡态势垒穿越，这表明飞秒动力学对催化的贡献。
The relevance of sub-picosecond protein motions to the catalytic event remains a topic of debate. Heavy enzymes (isotopically substituted) provide an experimental tool for bond-vibrational links to enzyme catalysis. A recent transition path sampling study with heavy purine nucleoside phosphorylase (PNP) characterized the experimentally observed mass-dependent slowing of barrier crossing (Antoniou, D.; Ge, X.; Schramm, V. L.; Schwartz, S. D. J. Phys. Chem. Lett. 2012, 3, 3538). Here we computationally identify second-sphere amino acid residues predicted to influence the freedom of the catalytic site vibrational modes linked to heavy enzyme effects in PNP. We mutated heavy and light PNPs to increase the catalytic site vibrational freedom. Enzymatic barrier-crossing rates were converted from mass-dependent to mass-independent as a result of the mutations. The mutagenic uncoupling of femtosecond motions between catalytic site groups and reactants decreased transition state barrier crossing by 2 orders of magnitude, an indication of the femtosecond dynamic contributions to catalysis.