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Increase the melting temperature of short, AT-rich primers and probes

Super T®—a duplex stabilizing, modified dT base

Add this modified base to increase the melting temperature (Tm) of primers and probes [1].

Quick facts

Availability: DNA and RNA
5', internal, and 3'
100 nmol to large scale
Purification: Standard desalt or HPLC
Ordering (modification codes):
5Super-dT/, /iSuper-dT/, /3Super-dT/

Super T (5-hydroxybutynyl-2'-deoxyuridine; Figure 1) is a modified dT base that can be included in an oligonucleotide primer and probe sequences to stabilize their hybridization [1,2]. Super T base-pairing with dA during primer or probe hybridization provides a ~2°C increase in melting temperature (Tm) per Super T insertion [1]. This Tm increase can be important when working with short primers or probes that are AT-rich.

The Super T modified base is extended normally by polymerases, including Taq polymerase.

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

How to order

To include Super T bases within your oligo, enter the IDT ordering symbol (/5Super-dT/, /iSuper-dT/, or /3Super-dT/) in the desired location within your sequence. You can request Super T modified oligonucleotides with standard desalt or HPLC purification.


  1. Belousov YS, Welch RA, Sanders S, et al. Single nucleotide polymorphism genotyping by two colour melting curve analysis using the MGB Eclipse Probe System in challenging sequence environment. Hum Genomics. 2004;1(3):209-217.
  2. Graham DP, Parkinson JA, Brown T. DNA duplexes stabilized by modified monomer residues: synthesis and stability. J Chem Soc. 1998:1131-1138.

Super T is registered trademark of Elitech Group and the respective modification is sold under a licensing agreement with Elitech Group.

For research use only. Not for use in diagnostic procedures. Unless otherwise agreed to in writing, IDT does not intend these products to be used in clinical applications and does not warrant their fitness or suitability for any clinical diagnostic use. Purchaser is solely responsible for all decisions regarding the use of these products and any associated regulatory or legal obligations. RUO22-1614_001

Published Dec 29, 2015
Revised/updated Nov 7, 2022