Biological Activity of novel glycosaminoglycan and interaction with binding proteins.

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We have very recently found a new glycosaminoglycan from African Giant Snail, Achatina fulica, and have characterized that this new glycosaminoglycan is consisting of homogeneous disaccharide (*4GlcNpAcalpha1*4IdoAp2Salpha) repeating unit. This polysaccharide, named acharan sulfate, has a unique sequence belonging in heparan sulfate family and shows angeogenesis activity.This study examined the hypothesis that contain oligosaccharide sequences in acharan sulfate have high affinity for consensus peptide sequences in proteins present in the extracellular matrix. A variety of different size of oligosaccharides in the range from disaccharide to tetradecasaccharide of acharan sulfate were prepared by partial enzymatic digestion. These oligosaccharides were used to isolate high affinity proteins, which were examined for composition and sequence. Oligosaccharide-protein interactions were examined for : 1. binding affinity (Kd) ; 2. binding specificity ; 3. Binding thermodynamics ; 4. binding … More orientation ; and 5. binding site structural requirements! Peptides will also be synthesized to contain variations of the consensus sequence and modified oligosaccharides such as N-de-acetylated and re-N-sulfonated acharan sulfate, were synthesized to help establish the structure activity relationship for oligosaccharide-peptide interaction. Native protein will be compared with synthetic peptide to confirm specificity of binding. Vitronectin and recombinant acidic fibroblast growth factor are the proteins to be studied because of the important biological consequences of their binding to acharan sulfate/heparin/heparan sulfate. Ultimately, these studies should lead to custom designed peptides that have increased oligosaccharide binding affinity to enhance or attenuate the activities associated with oligosaccharide-protein interaction. These oligosaccharides and peptides represent the starting point for new drug design focused on peptido-mimetics and sulfated oligosaccharide-mimetics. Such new therapeutic agents might be used to regulate a variety of biological processes including angiogenesis, metastasis, atherogenesis, immune responses, HIV infection, and thrombosis. Less