modified oligonucleotides

The most common modifications are at the end of the string – at the 3’ or 5’ end, or combined. The modifying molecule may be in the middle of the chain, the bases in the chain may be replaced by their analogs; spacers of different lengths and nature, functional groups or molecules may be inserted into the chain. Modified phosphate linkage may be in the chain in all or only in selected positions. Less frequent modifications or their combinations are recommended to be consulted first because there are many limitations for synthesis and for purification of the resulting product.