Amino Acid-Specific Attachment of a Protein to the Termini of Carbon Nanotube Without Affecting its Enzymatic Function

Abstract

In single-molecule measurement and manipulation of biological materials, as well as constructing biological devices by utilizing nano-materials, the interaction between biomolecules and nano-material largely affect the quality of the device and accuracy of the measurement. Especially, when a small number of the molecules are targeted, the way of attaching protein to the nano-material largely affects the result. We describe a strategy for site-specific conjugation of target proteins to carbon nanotubes. Non-natural amino acid, azido-tyrosine, was incorporated in a protein of interest at a desired position by utilizing amber mutation method. This azide group was then reacted with carboxyl group at the end(s) of nanotube through a set of cross linkers. We successfully demonstrated that calmodulin can be attached to the end of nanotube without losing its enzymatic functions. This approach allows the covalent conjugation of any nanostructure and/or nano-device to any proteins without affecting their biological functions.