Proceedings book download - 5Z.com

Proceedings of the 31 st European Peptide SymposiumMichal Lebl, Morten Meldal, Knud J. Jensen, Thomas Hoeg-Jensen (Editors)European Peptide Society, 2010Use of Ester-Containing Peptides Toward Understanding theFunctions of Amyloid Beta Peptide and Human InsulinYouhei Sohma 1,2 , Stephen B. H. Kent 2 , and Yoshiaki Kiso 11 Department of Medicinal Chemistry, Center for Frontier Research in Medicinal Science,Kyoto Pharmaceutical University, Kyoto, 607-8412, Japan; 2 Department ofBiochemistry and Molecular Biology, Institute for Biophysical Dynamics,The University of Chicago, IL, 60637, U.S.A.IntroductionChemical synthesis of peptides/proteins provides an efficient and versatile tool forelucidating in unique ways the molecular basis of function. This paper represents newinsights into the utility of ester-containing peptides toward understanding the functions ofbioactive peptides/proteins.Results and DiscussionEster InsulinAs a minimal surrogate for proinsulin we designed and synthesized an ‘ester insulin’precursor in which the A- and B-chains of insulin are covalently connected via an esterbond between the beta-hydroxyl group of ThrB30 and the gamma-carboxyl group of GluA4[1]. The ester linkage made the precursor molecule as favorable for folding/disulfideformation as does the 35 amino acid residue C-peptide in proinsulin. Folded ester insulinwas readily saponified to give insulin with full biological activity.With suitable optimization of its preparation, ester insulin may prove to be the key to asimple and effective route to the total chemical synthesis of insulin. The ester insulinprecursor polypeptide could be made by any of several synthetic routes, including thehybrid solution-solid phase methodology used for the cost effective large-scale manufactureof long peptides. We believe that ester insulin will be a useful intermediate for theefficient generation of insulin analogues in the research laboratory and for cost-effectivechemical manufacture of human insulins.O-Acyl Isopeptide of Amyloid Beta PeptidesReplacing the native amide (N-acyl moiety) by an ester (O-acyl moiety) at beta-hydroxylgroup of Ser or Thr residue (designated “O-acyl isopeptide”) changes the physical propertyof the native peptide [2]. Additionally, due to the presence of an additional amino group,the O-acyl isopeptide is generally hydrophilic. The target peptide is then generated from thecorresponding O-acyl isopeptide via an O-to-N intramolecular acyl migration.Based on the O-acyl isopeptide method, we are establishing an in situ system in whichmonomer amyloid beta peptide (Abeta) 1-42 is quickly produced from the water-solubleO-acyl isopeptide possessing an ester bond at the Gly 25 -Ser 26 sequence [3]. The generatedmonomer Abeta1-42 showed random coil-to-β-sheet conformational change,oligomerization, amyloid fibril formation and cytotoxicity. The intense and uncontrollableself-assembling nature of Abeta causes difficulties in preparing monomer Abeta, resultingin irreproducible or discrepant study outcomes. Thus, the O-acyl isopeptide system hasbeen used in Abeta-related Alzheimer’s disease research to more clearly explain thefunctions of Abeta. Further studies with Abeta mutants enabled us to identify new functionsof amyloid beta peptides.AcknowledgmentsWe are grateful for Drs. Atsuhiko Taniguchi and Hidehito Mukai (Kyoto Pharmaceutical University)for their collaborations throughout the study of O-acyl isopeptide.References1. Sohma, Y., Hua, Q-X., Whittaker, J., Weiss, M.A., Kent, S.B.H. Angew. Chem. Int. Ed. 49, 5489-5493 (2010).2. Sohma, Y., Sasaki, M., Hayashi, Y., Kimura, T., Kiso, Y. Chem. Commun. 124-125 (2004).3. Taniguchi, A., Sohma, Y., Hirayama, Y., Mukai, H., Kimura, T., Hayashi, Y., Matsuzaki, K., KisoY. ChemBioChem 10, 710-715 (2009).40