Linker and Spacer Phosphoramidites

The addition of primary amino groups to oligonucleotides are utilized to attach a variety of modifiers (eg. fluorescent dye, etc.) or attachment to a solid surface. Thermo Scientific amino linkers, TFA and MMT phosphoramidites are used for the addition of a primary amine to the 5′ position of an oligonucleotide. Phosphorylating hosphoramidites are used for addition of a phosphate group to the 5′ position of an oligonucleotide (final synthesis addition), or 3′-end when used as the first addition off of any solid support.

• The 5′ amino modifier amidites are supplied with MMT (27-0035) or TFA (27-1792) protection
• The MMT modifier allows for trityl-on purification of the resulting oligonucleotide and is a suitable choice when wanting to purify by reverse phase techniques.
• The base-labile TFA group is a good choice for 5′-amino modification when oligo purification isn’t necessary, prior to conjugation. The TFA group is removed during ammonia deprotection.
• Oligos with an amino modification can also be attached to surfaces in DNA chip applications.

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• Utilize C3 spacer amidite to incorporate a three carbon spacer or add sequentially to create longer spacer arms.
• Select C18 HEG amidite to reduce possible steric hinderance effects and/or protection from exonucleases.

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