Fig. 6. Binding of SZP to MuN and PiN peptides immobilised on microtitre plates. Different concentrations of GST PiN and MuN peptides were coated onto microtitre plates and probed with 50 ng of ¹²⁵I-SZP under different conditions. Competition was carried out with unlabelled SZP or peptides. (A) Saturable binding of ¹²⁵I-SZP to MuN peptide; (a) MuN peptide + ¹²⁵I-SZP; (b) MuN peptide + ¹²⁵I-SZP + excess unlabelled SZP (200 ng); (c) MuN peptide + ¹²⁵I-SZP + PiN peptide (in solution with ¹²⁵I-SZP); (d) MuC peptide + ¹²⁵I-SZP. (B) Saturable binding with ¹²⁵I-SZP to PiN peptide; (a) PiN peptide + ¹²⁵I SZP; (b) PiN peptide + ¹²⁵I-SZP + excess unlabelled SZP (200 ng); (c) PiN peptide + ¹²⁵I-SZP + MuN peptide (in solution with ¹²⁵I-SZP); (d) PiC peptide + ¹²⁵I-SZP. (C) Inhibition profile of binding of 600 nM ^*GST to SZP (1 µg) in the presence of excess peptides. (D) CD spectra of PiN and MuN peptides. CD spectra of the Pi-N peptide (a) has a characteristic minima of polyproline structure II at 206 nm, that shows that majority of the PiN peptide assumes an extended conformation. MuN peptide (b) has a minima below 200 nm and shows a typical pattern of random coil. ^*GST, radiolabelled GSTs.