Inverted bases

Quick facts

Availability: DNA
Location: 5′, internal, and 3′
Scales: 250 nmol to large scale
Purification: Standard desalt or HPLC
Ordering: Contact us

Insert 3′–3′ or 5′–5′ linkages

In addition to our catalog 3′ Inverted dT and 5′ Inverted Dideoxy-T modifications, we offer inverted DNA bases as a non‑catalog option (on request). Inverted bases (A, C, G, and T) allow you to design an oligo with a 3′–3′ or 5′–5′ reversed linkage (Figure 1). For example, with a reverse linkage, you can start a sequence in the 3′→ 5′ orientation, incorporate a 5′–5′ linkage in the middle, and finish in the 5′ → 3′ orientation.

Figure 1. Structure of 3′–3′ or 5′–5′ reversed linkages.

Inverted bases also allow you to add to the 3′-end of oligo modifications that are normally restricted to the 5′-end. Popular 5′-end modifications requested for addition to the 3′-end are: Acrydite™, HEX, and dideoxy-modified bases (other than dideoxy-C, which is regularly available through IDT). Dideoxy-modified bases are often used to block 3′ extension.

To order, contact us. Oligos containing inverted bases can be ordered as standard desalted oligos or with HPLC purification. Standard desalt is only available if other modifications in the sequence do not require the oligo to be HPLC purified.