Page 106 - Academic Press Encyclopedia of Physical Science and Technology 3rd Organic Chemistry

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414 Carbohydrates

FIGURE 21 Inhibition of gene translation with antisenese oligonucleotides. An oligonucleotide designed to complexes
with a segment of mRNA is used to arrest the synthesis of a vital protein.

attention of chemists because of their biological impor- groups (one on C-2 and one on C-3 ), which necessitates

tance and their relative ease of preparation. These char- that the 2 -OH group be protected to prevent the formation

acteristics become evident when the structures of the two of the undesired 2 → 5 phosphate bridge.

types of nucleotide monomers are examined. Thus, the
DNA monomers have only one free hydroxyl group (on B. Block Synthesis of Oligonucleotides

C-3 ), which, when esterified by the phosphate group of
another monomer, will form a phosphate bridge in the de- An oligonucleotide chain may be terminally phosphated
sired position (linking C-3 of one nucleotide to C-5 of (esterified) on C-5 or C-3 . Oligomers of the first type are

theother),whereasribonucleotideshavetwofreehydroxyl preparedfromnaturalnucleotidesbytreatinganacetylated

SCHEME 30 Some reactions of ribonucleotides.