Issue 19, 2017

Synthesis and structural investigation of 2-aminomethyl-3-(4-methoxy-phenyl)-propionic acid containing a peptide analogue of the amyloidogenic AS(6–7) sequence: inhibition of fibril formation

Abstract

The incorporation of a single β-amino acid moiety in a highly amyloidogenic peptide sequence resulted in the complete inhibition of amyloid fibril formation. The Boc-L-Phe-L-Leu-OMe sequence 1, which has sequence identity with the N-terminal AS(6–7) of the non-immunoglobulin amyloid fibril protein AS, which is responsible for rheumatoid arthritis, self-associates to produce fibrils. The D-Phe analogue peptide 2 shows an elongated ribbon-like morphology. However, the 2-aminomethyl-3-(4-methoxy-phenyl)-propionic acid containing analogue peptide 3 exhibits a polydisperse microsphere morphology. Moreover, fibrils from peptides 1 and 2 exhibit typical green-gold birefringence upon Congo red (CR) staining and show an amyloid-like morphological resemblance. However, the 2-aminomethyl-3-(4-methoxy-phenyl)-propionic acid modified peptide 3 does not respond to the Congo red assay. From X-ray crystallography, peptide 1 with the L-Phe residue adopts an extended structure, whereas the D-Phe analogue 2 adopts a kink-like structure. Both peptides 1 and 2 show twisted anti-parallel sheet-like structures at higher order assembly. However, peptide 3 adopts a nine-membered hydrogen bonded δ-turn-like structure in the solid state and self-associates to form a loop-like supramolecular structure through multiple intermolecular hydrogen bonds. The structural analysis presented herein may foster new studies for de novo design and therapeutics.

Graphical abstract: Synthesis and structural investigation of 2-aminomethyl-3-(4-methoxy-phenyl)-propionic acid containing a peptide analogue of the amyloidogenic AS(6–7) sequence: inhibition of fibril formation

Supplementary files

Article information

Article type
Paper
Submitted
30 Mar 2017
Accepted
18 Apr 2017
First published
18 Apr 2017

Org. Biomol. Chem., 2017,15, 4218-4225

Synthesis and structural investigation of 2-aminomethyl-3-(4-methoxy-phenyl)-propionic acid containing a peptide analogue of the amyloidogenic AS(6–7) sequence: inhibition of fibril formation

A. Paikar, M. Debnath, D. Podder, S. Sasmal and D. Haldar, Org. Biomol. Chem., 2017, 15, 4218 DOI: 10.1039/C7OB00797C

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