Introduction of Natural RNA Synthesis

RNA molecules perform a variety of roles in the cell including the coding, decoding, regulation, and expression of genes. The unique biological properties of some RNAs have attracted much attention. RNA oligonucleotides have been developed as therapeutics via antisense oligonucleotides (ASO) or small interfering RNA (siRNA) strategies for the treatment of diseases. Chemical synthesis of defined sequence RNA is the basis for studying and understanding the role and application of RNA.

The most used method for the solid-phase chemical synthesis of oligonucleotides is the phosphoramidite four-step process. Chemical synthesis of RNA is identical to that of DNA except for the need for an additional protecting group at the 2′ hydroxyl of ribose. This position is usually protected by tert-butyldimethyl silyl groups and remains stable throughout the synthesis process. The synthesis of RNA starts with removal of the dimethoxytrityl (DMTr) protecting group at the 5’-hydroxyl functionality of the nucleoside attached to the solid support by treatment with a mild acid. The subsequent addition of an activated nucleoside gives rise to the formation of a phosphite triester internucleotide bond. The unreacted nucleosides on the solid support are capped by derivatization of the 5’-hydroxyl groups to the corresponding acetyl esters. This step prevents the addition of subsequent nucleosides to this group, thereby minimizing the formation of undesired sequences. The last step is the oxidation of the phosphite triester group to the corresponding phospho triester. Multiple cycles of this four-step process generate oligonucleotides of the desired length and sequence, which are eventually cleaved from the solid support.

The efficiency of oligonucleotide synthesis depends greatly on the protecting groups used on the nucleotide phosphoramidites, which must be carefully chosen and selectively incorporated at different positions. Amerigo Scientific offers a wide range of phosphoramidites with protecting groups and supports for high-quality RNA synthesis.