Pac-dA

Phenoxyacetyldeoxyadenosine (Pac-dA) is a purine deoxynucleoside, in which the exocyclic amino group is protected with the Pac group during oligonucleotide synthesis. Use of the Pac-dA phosphoramidite is sometimes necessary when chemically synthesizing a labeled oligonucleotide in which the label moiety is not stable to the highly alkaline conditions required for removal of the base protecting groups on the standard dA, dC and dG monomers. Examples of such labels include TAMRA, Cy5 and HEX. When such is the case, Pac-dA is used in conjunction with Ac-dC (cat# 26-6901) and iPr-Pac-dG (cat# 26-6900) during synthesis, as their base protecting groups can be removed under significantly milder conditions, conditions that do not degrade the label.