Analysis of interaction between sulfated polysaccharides and HIV oligopeptides by surface plasmon resonance

Abstract This study aims to quantitatively investigate the interaction between sulfated polysaccharides with potent anti-HIV activity, dextran and curdlan sulfates with negatively charged sulfate groups, and poly- L -lysine as a model protein and oligopeptides from a HIV surface glycoprotein gp120 with positively charged amino acids using surface plasmon resonance (SPR) and dynamic light scattering (DLS) to elucidate the anti-HIV mechanism of sulfated polysaccharides. The apparent association- ( k a ) and dissociation rate ( k d ) constants of dextran and curdlan sulfates against poly- L -lysine were k a  = 6.92 × 10 4 –2.17 × 10 6  1/Ms and k d  = 4.29 × 10 −5 –2.22 × 10 −4  1/s; these kinetic constants were dependent on the molecular weights and degree of sulfation of sulfated polysaccharides. For interaction, the three oligopeptides from the HIV gp120 were peptide A 297 T R PNNNT RKR I R IQ R GPG R A 316 with several lysine (K) and arginine (R) in the V3 loop region, peptide B 493 PLGVAPT K A KRR VVQ R E KR 511 with several K and R in the C-terminus region, and oligopeptide C 362 K QSSGGDPEIVTHSFNCGG 380 with few basic amino acids in the CD4 binding domain. Sulfated polysaccharides exhibited strong interaction against oligopeptides A and B, ( k a  = 5.48 × 10 4 –2.96 × 10 6  1/Ms. and k d  = 1.74 × 10 −4 –6.24 × 10 −3  1/s), no interaction was noted against oligopeptide C. Moreover, the particle size and zeta potential by DLS indicated the interaction between sulfated polysaccharides and oligopeptides A and B, suggesting the anti-HIV mechanism of sulfated polysaccharides to be the electrostatic interaction of negatively charged sulfated polysaccharides and HIV at the positively charged amino acid regions.