Department of Applied Chemistry, Graduate School of Engineering, Osaka University , Suita 565-0871, Japan.
Frontier Research Base for Global Young Researchers, Graduate School of Engineering, Osaka University , Suita 565-0871, Japan.
J Am Chem Soc. 2017 Dec 6;139(48):17265-17268. doi: 10.1021/jacs.7b10154. Epub 2017 Nov 22.
Myoglobin reconstituted with iron porphycene catalyzes the cyclopropanation of styrene with ethyl diazoacetate. Compared to native myoglobin, the reconstituted protein significantly accelerates the catalytic reaction and the k/K value is 26-fold enhanced. Mechanistic studies indicate that the reaction of the reconstituted protein with ethyl diazoacetate is 615-fold faster than that of native myoglobin. The metallocarbene species reacts with styrene with the apparent second-order kinetic constant of 28 mM s at 25 °C. Complementary theoretical studies support efficient carbene formation by the reconstituted protein that results from the strong ligand field of the porphycene and fewer intersystem crossing steps relative to the native protein. From these findings, the substitution of the cofactor with an appropriate metal complex serves as an effective way to generate a new biocatalyst.
亚铁原卟啉 IX 重组肌红蛋白能催化苯乙烯与重氮乙酸乙酯的环丙烷化反应。与天然肌红蛋白相比，重组蛋白显著加速了催化反应，k/K 值提高了 26 倍。机理研究表明，重组蛋白与重氮乙酸乙酯的反应速度比天然肌红蛋白快 615 倍。金属卡宾物种与苯乙烯的反应表观二级动力学常数在 25°C 下为 28 mM·s。补充的理论研究支持通过重组蛋白形成有效的卡宾，这是由于卟啉的强配体场和相对于天然蛋白更少的系间穿越步骤。从这些发现中，可以看出用合适的金属配合物替代辅因子是生成新型生物催化剂的有效方法。
