Help - biotinylated peptide does not bind to CM

I think you should immobilize your biotin-tagged peptides with neutral pH and 0.3 M NaCl.

At neutral pH your ligands (low pI) should have a net negative charge. By adding 0.3 M NaCl you avoid the electrostatic repulsion between the surface and the negatively charged peptides.

Use a low flow rate for immobilization.

Good luck

Hi plasmon,

Thanx for your tip.

I will try it.

By neutral pH I suppose you mean 7 or 8?

I'll use PBS (pH=7.4) - the peptides should be negatively charged.

Slow flow rate = 10 ul/min? Less?

Hope it works (if it does you saved us lots of work and money )

Yes, pH 7.4 is good. I would work at 5 ul/min to increase the contact time between molecules.

It may be important to use a ligand concentration of at least 200 ug/ml.

Good luck