Artificial hydrolase based on carbon nanotubes conjugated with peptides.

An artificial enzyme was constructed by attaching short peptides with active sites (SHELKLKLKL, WLKLKLKL) onto carbon nanotubes (CNT). It was found that the combination of SHE amino acids was essential to form a catalytic triad. W was also incorporated into this artificial enzyme and acted as a substrate binding site, thus producing an enzyme model with synergism of 67.7% catalytic groups and 32.3% binding groups, CNT-(SHE/W)2:1-LKLKLKL. When the peptide SHELKLKLKL was attached with the catalytic triad site close to the surface of CNT, the composite had higher activity than a leucine-attached system terminated with the catalytic triad site, suggesting that CNT not only served as a platform for attaching active amino acids, but also created a hydrophobic microenvironment and facilitated the proton transfer process to enhance the catalytic activity. The artificial enzyme exhibited Michaelis-Menten behaviour, indicating that it was indeed a mimic of the corresponding natural enzyme. This work showed that a well-designed combination of CNT and short peptides containing active sites can mimic a natural enzyme.