Binding region and interaction properties of sulfoquinovosylacylglycerol (SQAG) with human vascular endothelial growth factor 165 revealed by biosensor-based assaysElectronic supplementary information (ESI) available: Experimental procedures, additional SPR sensorgrams, and detailed data of T7 phage display selection. See DOI: 10.1039/c1md00180a

Sulfoquinovosylacylglycerol (SQAG) is a sulfoglycolipid showing anti-angiogenic and radiosensitizing effects for treatment of solid tumors both in vitro and in vivo . Here we elucidated the interaction of SQAG with various growth factors and their cognate receptors for vascular formation using biosensor-based assays. The structure-binding relationship was also determined. Our results show that βSQDG selectively recognizes heparin binding domain (HBD) in human vascular endothelial growth factor 165 (hVEGF 165 ) with an affinity in the order of 10 −11 M. The presence of both a sulfate moiety and at least one C 18 length fatty acid chain is essential for binding. Conversion of anomeric configurations in SQAG did not alter the affinity with hVEGF 165 . This SQAG association inhibited T7 phage-displayed HBD binding to neuropilin-1 (NRP1), a VEGF receptor on the endothelial cell surface of blood vessels that specifically recognizes HBD in hVEGF 165 . Binding between sulfoquinovosylacylglycerol (SQAG) and hVEGF 165 was investigated in detail to reveal the binding kinetics and the specific region of interaction.