What is the recommended procedure for mild deprotection?
RESPONSE:Some linkages, modified bases, or modifiers may require more gentle deprotection conditions than the normal assault with ammonium hydroxide. The following procedure, described for a 0.2 mole synthesis, is mild and leads logically to Poly-Pak type DMT-on purification. This procedure has been used for oligonucleotides modified with Carboxy-dT and acridine. 1. Carry out the synthesis of oligonucleotides containing modified bases DMT-on, and oligonucleotides labelled with, for example, psoralen or acridine DMT-off. 2. Open the synthesis column and transfer the support to a suitable reaction vial. 3. Treat the support with 1mL of 0.4M methanolic sodium hydroxide (methanol:water, 4:1) for 17h at room temperature. 4. Pipette the supernatant from the support and neutralize with 1.5mL of 2M triethylammonium acetate. Either: 5. Desalt the oligonucleotide using normal procedures, lyophilize the resulting product and store the oligonucleotide at -20°C. Or: 5a. Dilute the neutralized solut
