Cyclic peptide oligomers synthesis

Other known oligonucleotide analogs include oligomers in which the heterocyclic bases have been modified [155] or replaced by other types of compound [156], Solid-phase syntheses of hybrids of DNA with peptides [157-163], with carbohydrates [164,165], and with PNA (peptide nucleic acids, see Section 16.4.1.2 [166-168]) have also been reported, and several strategies have been developed that enable the preparation of oligonucleotides with a modified 5 - or 3 -terminus [169-174] or of cyclic oligonucleotides [122,175], Various techniques for the parallel solid-phase synthesis of oligonucleotides have been developed for the preparation of compound libraries [176-181],... 

Chimeric peptides are unnatural constructs consisting of bioactive compounds from at least two different peptide(s) and/or protein(s) or two sequences from different parts of the same protein. Such multifunctional peptide combinations are prepared to enhance the biological activity or selectivity of their components. New biological effects can also be achieved with the chimera. In this chapter the synthesis of three different types of chimeric peptides will be described. In a linear chimera, two peptide epitopes from different parts of glycoprotein D (gD) of herpes simplex virus (HSV) are combined. A branched chimera, built from linear peptides, consists of tuftsin oligomers with immunostimulatory activity and an epitope peptide of HSV gD. The third compound is a cyclic chimeric molecule, where a-cono-toxin GI as a host peptide is modified by the incorporation of a core epitope from HSV gD as a guest sequence. 

Calix[n]arenes are cyclic condensation products of para-substituted phenol derivatives and formaldehyde [29], They are highly interesting for the development of sensitive coatings due to their conformational flexibility and the ease by which they may be modified chemically. Chemical modification can be done either in the meta position, or by reactions at the hydroxy group. In this way, bulky substituents [30], chelating substituents [31], aromatic residues [32], crown ethers [33,34], peptides [35,36], etc. can be introduced. A first approach to combinatorial synthesis of calix[4]arene receptors has been published by Reinhoudt and co-workers [37,38], who prepared calixarenes with different substituents. In solution, these calixarenes lead to formation of hetero-oligomers with barbiturates, and these hetero-oligomers were detected by MALDI-TOF mass spectrometry and H-NMR spectroscopy. 

Recent developments in the use of the CuAAC reactions in the synthesis, modification, and conformational control of peptidomimetic oligomers were reviewed in 2010 [32]. Both synthetic and biosynthetic methods have been implemented to afford peptides in cyclic or conformationally constrained configurations. 

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