PNA sequence

A possible form of coupling between membrane growth and template replication is assumed to proceed as follows. PNA molecules are planned to carry photosensitiser molecules. PNA acts as a catalyst for the light-driven fragmentation of the lipid and template monomer precursors. It is also assumed that certain PNA sequences provide the efficient charge transfer system necessary to realise the dynamic coupling. 

Additional factors that could influence the delivery efficiency and possible side effects of PNA-vector chimeras include the physical linkage between the PNA sequence and vector. Below we provide an overview of different conjugation strategies and provide a step-by-step protocol for disulfide bridge formation between PNA and carrier peptide. 

If PNA effects are measured a long time after the first treatment, additional quantities of PNA-peptide construct can be exogenously added to maintain intracellular PNA concentration. This is the case when the target mRNA of the PNA sequence encodes a protein with a long half-life. 

Figure 124. Crystal structure of a peptide nucleic acid duplex (left).901 For clarity, one strand is colored yellow and the other uses conventional atom colors PNA2-DNA triplex (right).710 Four chains are shown. The DNA chains are colored yellow and blue. The DNA sequence is 5 -(GAAGAAGAG)-3. The PNA chains are colored red and green. The PNA sequence is H2N- (CTCTTCTTC-His-Gly-Ser-Ser-Gly-His-CTTCTTCTC) -C02H.

This relation constant may be calculated from the PNA sequence by employing the following extinction coefficients. 

Scheme 1.14. DNA assay using P2 (shown in green) and PNA-C (shown in blue, where C is FI). The system responds depending on whether the ssDNA (shown in red) is complementary or noncomplementary to the PNA sequence [74]. Copyright 2002 National Academy of Sciences, U.S.A.

PNA, first introduced by Nielsen et, is able to form stable structures with either DNA or RNA, but has the unique property that it is able to strand-invade a DNA duplex, and is best accomplished with pyrimidine-rich PNA sequences. It has been reported that a pyrimidine hexamer of PNA combined with a mixed sequence decamer can strand-invade both duplex and triplex structures. Decreasing the pyrimidine region below six residues leads to a decrease in effectiveness of strand-invasion. Two PNA strands connected by... 

Purine-rich PNA sequences require double coupling to improve the purity and yield of the final compound. 

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