Researcher: I am synthesizing a 60' mer 5' amine-modified oligonucleotide to be used to covalently couple to magnetic particles using the Solid Phase Oligo Couple-IT™ Kit. Since only approximately 60% of the oligos will be full length, do I need to purify the oligo before coupling?

TechTALKer:For most coupling reactions using oligos that are less than 75 bases it is not necessary to purify the modified oligo. The coupling chemistry requires a reactive primary amine on the oligonucleotide. DNA synthesizers synthesize oligonucleotides from 3' to 5'. When synthesizing an oligo with a 5'-amino modifier only the full length sequences will contain the reactive amine, therefore, it is not necessary to purify the full-length population. However, as the length of the sequence increases, the proportion of full length oligos decreases and the actual amount of modified DNA will be less than calculated by OD₂₆₀. Therefore, for sequences that are greater than 75 bases purification will allow you to accurately calculate the amount of amine-modified molecules in the coupling reaction. Note: The amino groups associated with guanine and cytosine are not reactive and will not bind to the activated MPG^® LCA particles (MPG^® LCA is sold separately or as part of the kit).

Related Product Pages

• MPG® Long Chain Alkylamine (LCA)
• Solid Phase Oligo COUPLE-IT™ Kit