Modified PNA Monomers

Modified PNA Monomers

Creative Peptides' Modified PNA Monomers can be used to modulate protein and nucleic acid interactions.

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Introduction

PNA is a nucleic acid analog in which the normal phosphate linkage found in DNA and RNA is replaced by a neutral peptide-like N-(2-aminoethyl) glycine backbone. Compared with DNA or RNA, PNA has better chemical and biological stability. (1) PNA is not easily degraded by nucleases and proteases. (2) There is no bridge of electronegative phosphodiester bond in the PNA structure, so it is neutral. This avoids interaction with plasma, thereby reducing the potential for nonspecific effects. However, due to the structural characteristics of the electron-neutral framework of PNA itself, PNA is poor in water solubility and biological availability and tends to self-aggregate. These shortcomings are currently the main obstacles to its application in the field.

So far, various methods have been used to modify the PNA backbone and bases with the primary aim of:

• To improve the water solubility of classical PNA.
• To enhance hybridization affinity and sequence selectivity.
• To improve bioavailability.
• To expand the range of applications of PNA in molecular biology.

Modification of PNA monomers

➢ Modification to PNA backbone

• Modifying the chemically active sites at both ends of the monomer (N-terminal and C-terminal).
• Changing the number of bonds between the N-terminal and C-terminal of the monomer, i.e., changing the backbone length.
• Introducing a modifying group at the α-position, replacing glycine with a chiral amino acid.
• Introducing a modification group at the γ-position with a chiral amino acid.
• Introducing a ring structure between the N-terminal and C-terminal of the monomer.

➢ Modification to PNA bases

It is mainly modified at certain sites on the nucleic acid bases or replaced with other nitrogenous groups. Since the modified PNA sequence will be used to form a higher structure, the modification of the monomer cannot affect the formation of inter-base hydrogen bonds.

• Introducing a functional group at the 5-position of uracil, since this position is not involved in hydrogen bond formation and does not introduce large stereochemical barriers.
• Introducing natural base analogs such as pseudocytosine and 2,6-aminopurine.
• Heterocyclic modifications of thymine and cytosine.
• Introducing bases capable of fluorescent labeling.

➢ Simultaneous modification of PNA backbone and bases

Currently, most of the PNA monomers are modified on the backbone or bases separately, and simultaneous modification of monomers has not been reported. When performing simultaneous modification of bases and backbones, the principle of orthogonality of protecting groups should be fully considered to facilitate the sequence synthesis of PNA. In addition to the protection of amino groups, the protection of amino acid side chains should also be considered. When introducing the protecting group on the base, the orthogonal protection with the protecting group of the amino group and the protecting group of the amino acid side chain on the backbone should also be fully considered.

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For Research Use Only. Not For Clinical Use.