Conformation change of α-synuclein(61-95) at the air-water interface and quantitative measurement of the tilt angle of the axis of its α-helix by multiple angle incidence resolution spectroscopy

Chengshan Wang, Shiv Kumar Sharma, Oladimeji Sunday Olaluwoye, Saad Ayidh Alrashdi, Takeshi Hasegawa, Roger M. Leblanc

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

Various techniques have been developed to determine protein's structure to understand how proteins work. Compared with X-ray crystallography requiring proteins to form single crystal structure and NMR which usually needs long time measurement, surface FT-IR techniques are able to quickly determine the tilt angle (the key information to determine whether the α-helix is transmembrane) of peptides/proteins in a monolayer at the interface (e.g. membranes). Specifically, for α-helical peptides/proteins in membrane, the tilt angle of the axis is one of the key information. In this paper, Multiple Angle Incidence Resolution Spectroscopy (MAIRS), a recently developed surface FTIR technique, was applied for the first time to quantitatively determine the tilt angle of the axis of α-helical model peptide related to α-synuclein (α-syn). α-Syn is a 140-amino-acid presynaptic protein whose aggregation is the hallmark of Parkinson's disease (PD). It is difficult for α-syn to form a single crystal structure and the primary structure of α-syn constitutes three domains: the N-terminus containing residues 1–60; the nonamyloid component (NAC) which spans residues 61–95 and is highly prone to aggregation; and C-terminus with residues 96–140. Here, the NAC part (i.e., α-syn(61–95)) responsible for the aggregation was found to change its unstructured conformation in aqueous solution to α-helix at the air-water interface by circular dichroism and MAIRS. In addition, the instinct power of MAIRS to quantitatively measure the tilt angle of the axis of α-helical α-syn(61–95) in monolayer was fully exhibited. Therefore, MAIRS is a potential supplemental technique to X-ray crystallography and NMR to determine the structure of membrane peptides/proteins.

Original languageEnglish (US)
Article number110401
JournalColloids and Surfaces B: Biointerfaces
Volume183
DOIs
StatePublished - Nov 1 2019

Keywords

  • Amide I band
  • Circular dichroism
  • Conformation change
  • FT-IR
  • Langmuir monolayer
  • MAIRS
  • Tilt angle
  • α-Synuclein

ASJC Scopus subject areas

  • Biotechnology
  • Surfaces and Interfaces
  • Physical and Theoretical Chemistry
  • Colloid and Surface Chemistry

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