Protein purification with light
Proteins from cell extracts or culture supernatants are currently purified rapidly using affinity chromatography.
The researchers present the light responsive Azo-tag, a short peptide comprising p-(phenylazo)-L-phenylalanine (Pap), whose side chain can be switched from its trans-ground state to the metastable cis-configuration by irradiation with mild UV light.
Since only transPap shows strong affinity to α-cyclodextrin (α-CD), a protein exhibiting the Azo-tag selectively binds to an α-CD chromatography matrix under daylight or in the dark but elutes quickly under physiological buffer flow when illuminating the column at 355 nm.
The researchers purified enzymes and antibody fragments using this light-controlled single-step purification – called Excitography.
The authors dis not use competing agents or harsh buffer conditions normally used in affinity chromatography.
