Why can DAP be used to elute a protein in affinity chromatography?
In this report, diaminopropane is used to elute a lectin from an affinity column. They mention the pH, which is the key to the question.


  The  bound  lectin was  eluted  with  20  mM diaminopropane  containing  0.15M NaCl,  pH ~11.


The diaminopropane is unbuffered, and the high pH weakens the interactions between lectin and carbohydrates.