Carbon biological function

Many years have passed since the early days of AFM, when adhesion was seen as a hindrance, and it is now regarded as a useful parameter for identification of material as well as a key to understanding many important processes in biological function. In this area, the ability of AFM to map spatial variations of adhesion has not yet been fully exploited but in future could prove to be particularly useful. At present, the chemical nature and interaction area of the AFM probe are still rarely characterized to a desirable level. This may be improved dramatically by the use of nanotubes, carbon or otherwise, with functionalized end groups. However, reliance on other measurement techniques, such as transmission electron microscopy and field ion microscopy, will probably be essential in order to fully evaluate the tip-sample systems under investigation. 

Kam, N.W.S. and Dai, H.J. (2005) Carbon nanotubes as intracellular protein transporters generality and biological functionality. Journal of the American Chemical Society, 127 (16), 6021-6026. Heller, D.A. et al. (2005) Single-walled carbon nanotube spectroscopy in live cells towards long-term labels and optical sensors. Advanced Materials, 17 (23), 2793-2799. 

Kam NWS, Dai HJ (2005) Carbon nanotubes as intracellular protein transporters Generality and biological functionality. J. Am. Chem. Soc. 127 6021-6026. 

Carbon electrodes can be made from a number of various crystalline forms of carbon. The two most common versions are the carbon paste electrode and the glassy carbon electrode. In Chapter 11, devoted to the electrochemistry of biological functions, it will be seen that pyrolytic graphite electrodes have also found wide application. Recently, attempts to use carbon-nanotube electrodes have been also proposed.9... 

Phenylglycines are important components of the vancomycin/teicoplanin antibiotics, and the conforma-tionally restricted amino acids contribute to the unique architecture and biological function of these clinically important NRPs. 4-Hydroxyphenylglycine is produced from L-tyrosine in a pathway that involves three enzymes. In the key step, a nonheme iron oxidase catalyzes the oxidative decarboxylation of the a-keto acid derivative of L-tyrosine resulting in loss of carbon dioxide and generation of the phenylglycine carbon framework. 

Phosphate esters, particularly AMP, ADP and ATP, have vital biological functions and this fact has generated intense interest in their reaction mechanisms. Subtle stereochemical experiments, such as the use of isotopically chiral compounds, have been important and, since all biological phosphorylation reactions appear to involve metal ion catalysis, the stereochemistry of phosphate ion coordination has also been subject to much attention.229,230 Apart from its biological significance, this work has revealed some interesting contrasts with the stereochemistry of ligand systems in which saturated carbon units link the donor atoms. 

Biological functionalization of nanomaterials has become to be of significant interest in recent years owing to the possibility of developing detector systems. Noncovalent immobilization of biomolecules on carbon nanotubes motivated the use of the tubes as potentially new types of biosensor materials [207-210] (a review on carbon nanotube based biosensors was recently published by Wang [211]). So far, only limited work has been carried out with MWCNTs [207-210]. Streptavidin was found to adsorb on MWCNTs, presumably via hydro-phobic interactions between the nanotubes and hydrophobic domains of the proteins [210]. 

The nature and position of the carbon-nitrogen linkage in the 2-amino sugars endows them with unique properties and biological function that differ widely for example, from those of the nucleotide and nucleoside type of molecule. These substances are theoretically derived by condensation of an amine with carbon atom 1 of a hexose. Although no biogenetic relationship between these two groups has yet been discovered such a possibility cannot be discounted. 

The emergence of life brought—indeed depended upon—a kaleidoscopic variety of separation processes. Mechanisms evolved to sort out and thus organize cellular components. Carbon and oxygen were split apart by photosynthesis, leading to a carbon-rich biosphere and an oxygen-rich atmosphere. Trace metals were selectively retained to participate in biological functions. 

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