Pseudoproteoglycan (pseudoPG) probes that simulate PG macromolecular structure for screening and isolation of PG-binding proteins

online first / \r\nReceived: 28 July 2008 / Revised: 30 September 2008 / Accepted: 8 December 2008 / Published online: 21 February 2009The original publication is available at www.springerlink.comA proteoglycan (PG) monomer is a macromolecule consisting of one or more glycosaminoglycan (GAG) chains attached to a core protein. PGs have signaling roles and modulatory functions in the extracellular matrix and at the cell surface. To elucidate the functions of higher-order PG structures, pseudoPGs that imitate the PG structure were prepared to develop probes and affinity adsorbents. Poly-L-lysine (PLL) or polyacrylamide (PAA) was coupled with various GAGs, then biotinylated, and the remaining amino groups were blocked to obtain the pseudoPG probes, biotinyl PLL (BPL)- or PAA (BPA)-GAGs. Lactoferrin exhibited 30-times higher affinity toward BPL-heparin than the conventional single-strand probe, biotin-hydrazide-heparin.Heparin-PLL was immobilized on a formyl-Sepharose and compared with the Hep-Sepharose in which heparin was directly immobilized to amino-Sepharose. Screening for ligands in normal rat brain revealed several proteins that specifically bound to either of the two adsorbents, indicating that the heparin-binding proteins exhibit specific recognition depending on the higher-order structure of the PG