Spacer phosphoramidites are used during oligonucleotide synthesis to introduce a spacer arm into the sequence. Multiple additions of the different spacer molecules allow the precise length of the spacer arm to be controlled.
Several spacer modifications are available. Spacers C3, C8 (octanediol), 9, C12, HEG (hexaethylene glycol) and 18 can be used to bridge sections of oligos where no appropriate binding is possible.
The 3’ spacer-C3-CPG is used to introduce a terminal spacer which acts as a blocker of exonuclease and polymerase activity at the 3’ end.
Spacer-C18 can be used to add a very hydrophobic section to an oligonucleotide.
The dSpacer is used to create a stable abasic site within an oligonucleotide.