Template for Electronic Submission to ACS Journals - BioTechnologia

396J. Brzezińska, K. Adrych-Rożek, Z. Jahnz-Wechmann et al.Table 4. Melting temperatures of chromophores (Schmucker et al., 2012)Modification Sequence Tm [°C] ) Tm [°C]21 63.3 !7.4 a22 68.6 !2.1 a23 3N-GXG-5N 68.4 !2.3 a24 5N-CCC-3N 65.7 !5.0 a25 66.2 !4.5 aFig. 10. Influence of single nucleotides on the aggregationof oligomers (Nussbaumer et al., 2012)Synthetic non-isotopically labeled oligonucleotidesare widely used for sequencing and medical diagnostics,and as probes in molecular biology. Structural modificationsof the nucleotide units facilitate the delivery of thenucleic acid into the cells or increase their enzymaticresistance (Guzaev et al., 1996). Langenegger described(Langenegger et al., 2006) synthesis and spectroscopicstudies of DNA duplexes that were modified with structurallysimilar but electronically disparate molecules,e.g. pyrene S and phenanthrene P (Fig. 7).As a result of the above, the placement of nucleosidesresidues in both an interstrand pyrene and phenanthreneresidues makes it possible to observe differencesin the spectroscopic properties of the modified duplexes.In the model in which the interaction between pyrenemoieties is assumed, the strong absorption (or emission)that is characteristic of pyrene excimer was observed.Furthermore, the interstrand-stacking interactions betweenthe polyaromatic residues take place and can be observedwith a high degree of selectivity in pyrene-pyrenebut not phenanthrene-phenanthrene analogs (Langeneggeret al., 2006). This allows the design of DNA hybridswith interesting spectroscopic properties by selectingthe places of incorporation of polyaromatic buildingblocks. Oligonucleotides modified by non-nucleosidic residuescan be used for the creation of nanomaterials oras fluorescent probes used for diagnostic purposes.To develop artificial functionalities of DNA the oligonucleotide2N-deoxyribose residue was replaced with anacyclic linker (Schmucker et al., 2012). The linker was toprovide a higher thermal DNA stability and appropriateflexibility of the chromophore to intercalate. The ethidiumresidue was attached as a linker to the (S)-1-amino-1,3-propanediol (18) and (S)-threoninol (20) and theiraffinity for DNA stacking ability was investigated (Fig. 8).Tm values of modified DNA showed a minor influenceof the structure of acyclic linkers (18, 20) onchromophore intercalation. Moreover, the stability wasonly slightly higher in comparison to the unmodifiedDNA double strand. As an alternative, DNA nucleoside