There are many applications for reverse linked nucleotide modifications of oligonucleotides. They impart nuclease resistance and allow the study of strand orientation effects on molecular biological function. When placed internally the remaining portion of the oligo must be synthesized with reversed polarity. This and other such complicated constructs, must be quoted on a case-by-case basis. Please see internal modification prices below to determine the cost of the reversed polarity portion of your oligonucleotide, if applicable.