Specific Vectorial Immobilization of Oligonucleotide‐Modified Yeast Cytochrome c on Carbon Nanotubes

Abstract

Iso-1-cytochrome c from the yeast Saccharomyces cerevisiae (YCC) contains a surface cysteine residue, Cys102, that is located opposite to the lysine-rich side containing the exposed heme edge, which is the docking site for enzymes. Site-specific vectorial immobilization of YCC via Cys102 on single-walled carbon nanotubes (SWNT) thus provides a selective interface between nanoscopic electronic devices and complex enzymes. We have achieved this by modification of Cys102 with an oligonucleotide (dT(18)). Atomic force microscopy, fluorescence imaging, and cyclic voltammetry show the specific adsorption of YCC, modified with dT(18), on the SWNT sidewall with retention of its native properties. Pretreatment of the SWNT with Triton-X405 blocks the nonspecific binding of untreated YCC but does not interfere with binding of the oligonucleotide-modified YCC.

Carbon Nanotubes for Electronic and Electrochemical Detection of Biomolecules

“…[109] In another study, oligonucleotide-modified yeast cyt c adsorbed strongly to SWNTs, and gave small reversible voltammograms after background subtraction. [130] A number of other heme proteins have been shown to undergo direct electron exchange with carbon MWNT mat electrodes. [37,117,118] However, except in a few special cases (e.g., glucose oxidase), nanotube mat electrodes do not seem to provide significant advantages in reversibility or signal-to-noise ratio compared to the best redox protein films on conventional electrodes.…”

Direct Electrochemistry of Redox Enzymes as a Tool for Mechanistic Studies

“…In a subsequent paper, the authors describe the attachment of cytochrome c to single-walled carbon nanotubes in an orientation that will certainly prove appropriate for relaying electrons to redox enzymes. 254 Conductive wiring of an immobilized photosynthetic reaction center 255 or sulfite oxidase 256 to an electrode by horse-heart cytochrome c was also reported. In ref 257, Demaille and co-workers describe a reconstituted photosynthetic electron transfer chain where the proteins were solubilized (rather than adsorbed); they could examine in detail the inter-protein interactions (ferredoxin/PSI and ferredoxin/FNR) and could determine binding and dissociation rates and a shift of the reduction potential of ferredoxin when complexed with FNR.…”

Lipase immobilized carbon nanotubes for conversion of Jatropha oil to fatty acid methyl esters

“…Due to their strong mechanical properties and chemical stability, the carbon nanotubes (CNTs) are seen as very effective support for enzyme immobilization. Enzyme-CNT bionanoconjugates have found applications in biosensors, biofuel cells and biocatalysis [26,27]. It has been demonstrated that the immobilization of enzymes on to the CNT helps in enhancing the overall bioactivity and stability [26,27].…”