Materials

• 0.1M NaHC03 pH9
• DMSO
• NHS-Biotin (N-Hydroxysuccinimidobiotin, Sigma #H-1759)
• PBS

Procedure

1. Dialyze the sample against carbonate buffer.
2. After dialysis, adjust sample to 1 mg/ml (or less).
3. Prepare 1 mg/ml solution of NHS-Biotin in DMSO.
4. Add NHS-Biotin in DMSO to antibody at desired ratio e.g. for 1:8 ratio add 125 ml of NHS-Biotin to 1mg of Ab
5. Incubate on rotator for 4 hours at room temperature or overnight at 4C.
6. Dialyze against PBS.