We are using your protein-oligo kit to attach peptides to oligos. My peptide precipitates out of solution once labeled with HyNic. What can I do to prevent this?

You should dissolve your peptide in DMF. Many peptides are difficult to work with because of solubility issues. Perform the modification reaction with 1 mole equivalent of HyNic, and the reaction should be performed in DMF with 2 mole equivalents of TEA (triethylamine). The peptide should be modified, and stay in solution. The 4FB-oligo should be dissolved in a 50:50 mix of conjugation buffer and DMF. Perform the conjugation reaction in this mixture.