Biomolecules Peptides, specific proteins

In recent years, there has been a lot of research in the utilization of biomolecule-functionalized nanoparticles for the formation of hybrid nanostructures. While much effort was spent on solution systems, there are some examples that exploit the binding specificity of the biomolecules, for example, proteins, peptides, and DNA to assemble nanoparticles on surfaces. 

This mode of separation, as the name suggests, uses stationary phases with a special affinity for a specific analyte. The affinity ligand immobilized on the stationary phase varies dramatically from peptide, to protein, to oligonucleotide, to monoclonal antibody. In some cases the target molecule is labelled with an affinity tag to simplify the separation. This approach is common in the synthesis of recombinant proteins where the system can be engineered so that the target biomolecule expresses a tag such as polyhistidine. A stationary phase functionalized with aminodiacetic acid and nickel chelate is then used to fish out the required molecule by chelating with the polyhistidine tag. 

The advent of both ESI and MALDI revolutionized the analysis of large biomolecules of low volatility such as peptides and proteins by their capability to form stable ions with little excess energy, enabling the determination of molecular weights even in protein mixtures. To obtain information specific to the primary structure of proteins, however, principles such as the activation of molecules via collisions with small neutral molecules, which have been used in the study of gaseous ion chemistry for decades, had to be adapted and helped to propel mass spectrometry to being of the most important tools in the field of proteomics. 

This chapter focuses on how fluorinated methionine analogues interact with biological systems. Specifically the compounds L-monofluoromethionine (l-(S)-(monofluoromethyl) homocysteine MFM), L-difluoromethionine (L-(S)-(difluoromethyl)homocysteine DFM), and L-trifluoromethionine (L-(S )-(trifluoromethyl(homocysteine) TFM) will be the subject of this article (Figure 17.1). A discussion of their syntheses and chemical and conformational properties will be presented. This will be followed by a discussion of their incorporation into peptides and proteins and the properties of the resulting fluorinated biomolecules. The 19F NMR spectroscopic characteristics of these biomolecules will be covered along with how these resonances have revealed information on the properties of the difluoro- and trifluoromethyl moiety (and on the proteins as well ). Further elaboration of these amino acids with metalloenzymes completes the survey. 

We can also mention the use of bio-sourced building blocks based on cellulose or dextran. Kadla et al. described value-added materials from naturally abundant polymers for system that may serve as a platform for the design and development of biosensors [197]. A hierarchically strucmred honeycomb film from dextran-ft-PS amphiphilic linear diblock copolymers has also been described by Chen et al. leading to ordered porous bio-hybrid films. [198] Honeycomb patterned surfaces functionalized with biomolecules for specific recognition of proteins or bacteria have been also achieved either by self-assembly of amphiphilic copolymers based on galactose moieties [155] or by post-modification with peptide sequences [199]. 

Many natural biomolecules, like peptides and proteins, interact and self-assemble to form delicate structures that are associated with specific functions (33). Ligaments and hair, for example, are assembled from collagen and keratin, respectively. DNA transcription is initiated by self-assembly of transcription factors, RNA polymerase, and DNA. Systematic studies and analysis of these natural existing self-assembly systems provide insight into the chemical and structural principles of peptide self-assembly, which inspires the development of molecular self-assembly as a new approach for fabrication of novel supramolecular architectures. 

---