Universal Support III PS
atalog Number: 26-5010-xx
Description: Universal Support III PS
| 1-Dimethoxytrityloxy-2-O-dichloroacetyl-propyl-3-N-ureayl-polystyrene |
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| Coupling: This support should be used in a manner identical to normal protected nucleoside support since it contains the DMT group. |
| Deprotection: See Technical Bulletin for details (Technical Bulletin).Note: This product is not compatible with cyanoethyl protecting group removal protocols using hindered bases such as DEA or DBU. Removal of the cyanoethyl groups prior to cleavage will prevent the release of the oligonucleotide from the support. |
| Storage: Refrigerated storage, maximum of 2-8°C, dry |
| Stability in Solution: 2-3 days |
UNIVERSAL SUPPORT III
The key step in the use of any universal support in oligonucleotide synthesis is the dephosphorylation of the 3’-phosphate group to form the desired 3’-hydroxyl group. Azhayev1,2 has excelled in the investigation of neighboring group assistance in the dephosphorylation reaction. Amide groups may be considered to be weak N-H acids and can display basic properties in ammonium hydroxide or aqueous methylamine. (±)-3-Amino-1,2-propanediol was used to form a novel universal support. In our original US II support, a succinate linker attaches the 3-amino group to the support and the 2-OH is protected with a base-labile group to set up an amide assisted elimination in mildly basic conditions. In this way, the dephosphorylation reaction would eliminate the desired 3’-OH oligonucleotide into solution and the product of any ß-elimination competing side reaction would remain bound to the support. A further improvement has been achieved by using a carbamate group to connect the universal linker to the support, now called Universal Support III. The structures of the two supports are shown below right. Because the universal linker is unchanged and the succinate or carbamate groups remain attached to the support, we use the same catalog numbers for US II and III. Using Universal Support II or III, an oligo yield of > 80% can be achieved on CPG supports and > 95% on polymeric supports, with purity equivalent to the same oligo prepared normally.
Conditions for Cleavage and Deprotection are outlined in the table opposite. Universal Support II/III has been shown to generate oligonucleotides with the same efficacy in polymerase extension reactions as regular oligos. Despite the mild elimination reaction, oligonucleotides up to 75mer in length can be prepared routinely without loss of oligo during the synthesis cycles. This support is also used for the production of siRNA oligos.
STERLING SUPPORTS
All Glen Research CPG supports use the standard long chain alkylamino (lcaa) linker but differ in the glass pore size, 500Å, 1000Å or 2000Å. The 500Å support is appropriate for shorter sequences, while the 1000Å supports perform better in the synthesis of longer (>30-mer) DNA sequences. The 2000Å support is best for very long (>150-mer) oligonucleotides. We have instituted an additional QC test for supports to show the length of oligo that can be prepared before a drop-off in coupling due to steric effects begins to occur. The drop-off point is recorded in the Certificate of Analysis. All Glen Research supports are fully end-capped to ensure that the CPG surface is totally inert, thereby avoiding the introduction of impurity sequences containing deletions at the 3’-terminus.
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