Reactive Oligonucleotide Handles

When should I use TCO-tetrazine chemistry?

TCO-tetrazine ligation is useful when very fast bioorthogonal reaction kinetics are needed, especially for imaging, rapid conjugation and complex biological workflows.

What is the difference between azide and DBCO?

Azide is commonly used with alkyne partners in CuAAC click chemistry or with DBCO/BCN in copper-free SPAAC chemistry. DBCO is a strained alkyne that reacts with azides without copper.

What is a reactive oligonucleotide handle?

A reactive oligonucleotide handle is a chemical functional group incorporated into a DNA or RNA oligo to enable selective conjugation to another molecule, surface or material.

Which handle is best for protein conjugation?

 Maleimide is commonly used for cysteine or thiol-containing proteins, while NHS esters react with primary amines such as lysine side chains or amino-modified proteins.

Can multiple reactive handles be incorporated into one oligonucleotide?

 Yes. Orthogonal combinations can be used for multi-step conjugation, but handle compatibility, spacing and purification should be reviewed carefully.

Are reactive handles available internally?

 Many handles can be placed at the 5' terminus, 3' terminus or internal positions depending on chemistry, sequence design and synthesis feasibility.

What spacer should I choose?

 C3, C6, TEG and PEG-style spacers are commonly used. Longer spacers often improve accessibility and reduce steric hindrance during conjugation.

What QC is recommended?

 HPLC or PAGE purification with mass spectrometry identity confirmation is recommended. Post-conjugation HPLC, LC-MS, UV/Vis or gel analysis may be useful for complex constructs.

What is the difference between CuAAC and SPAAC?

 CuAAC uses a copper catalyst to accelerate azide-alkyne cycloaddition, whereas SPAAC uses strained alkynes such as DBCO or BCN to react with azides without copper. SPAAC is often preferred for copper-sensitive biological workflows.

Can reactive handles be combined with fluorescent dyes or quenchers?

 Yes. Reactive handles are frequently combined with fluorophores, quenchers, affinity tags, modified bases and other oligonucleotide modifications to create multifunctional probes, conjugates and detection systems. Compatibility depends on modification placement, purification requirements and the intended application.