Who will lead the catalysis of nanozymes?

In addition to the role of iron in catalysis, other atomic structures may also mediate the catalytic process.

In fact, there are two carboxyl groups in the heme structure. It is reported that the carboxyl group facilitates binding to the substrate. The research group of Professor Gao Lizeng of the Nanoenzyme Engineering Laboratory of the Chinese Academy of Sciences [1] found that the carboxyl group in the iron oxide nanoparticles can improve the catalytic performance. The direct modification of porphyrin can also improve the activity of nanoparticles, which may be attributed to the coordination effect of porphyrin and iron on the surface of nanoparticles [2]. At the same time, amino acid residues also play a certain role in the catalysis process. In particular, the histidine imidazole in HRP plays an important role in the coordinated binding of iron and water. Inspired by this, the modification of histidine on the surface of iron oxide nanoparticles is essential to improve peroxidase-like and catalase-like activities [3]. Compared with bare iron oxide nanoparticles, a single histidine modification can increase the catalytic efficiency by more than 20 times.



Simulation analysis shows that the hydrogen bond formed by histidine and hydrogen peroxide (initial state) not only weakens the strength of the O–H bond, but also makes the electronegativity of O stronger. The former process is conducive to the cleavage of the O-O bond in hydrogen peroxide, and the latter process is conducive to enhancing the adsorption of hydrogen peroxide on the Fe3O4 nanoenzyme (final state). Therefore, His42 plays a similar role in the active center of HRP. The influence of iron and terminal residues in catalytic activity indicates that a certain structure is necessary for the formation of nanozyme active sites.




references:

1. Yang CH, Du JJ, Peng Q, Qiao RR, Chen W,Xu C, Shuai ZG, Gao MY (2009) Polyaniline/Fe3O4 nanoparticle composite: synthesis and reaction mechanism. J Phys Chem B 113(15):5052– 5058

2. Liu QY, Li H, Zhao QR, Zhu RR, Yang YT, Jia QY, Bian B, Zhuo LH (2014) Glucose-sensitive colorimetric sensor based onperoxidase mimics activity of porphyrin-Fe3O4 nanocomposites. Mat Sci Eng C Mater 41: 142–151

3. Fan KL, Wang H, Xi JQ, Liu Q, Meng XQ, Duan DM, Gao LZ, Yan XY (2017) Optimization of Fe3O4 nanozyme activity viasingle amino acid modification mimicking an enzyme active site. Chem Commun 53(2): 424–427