Synthesis of an immunosuppressant SQAG9 and determination of the binding peptide by T7 phage display

SQAG9, a new class of immunosuppressive sulfoquinovosylacylglycerol, and its biotinylated derivatives have been synthesized. A T7 Phage library, composed of random cDNA fragments from Drosophila melanogaster, displayed a possible binding peptide of 14 amino acids. The immobilized synthetic peptide on a sensor chip showed a dissociation constant of KD=1.5×10−6 against SQAG9 in a surface plasmon resonance experiment.