Copper-induced oligomerization of peptides: a model study

Area of Science:

• Analytical Chemistry
• Biochemistry
• Spectroscopy

Background:

• Metal ion binding to peptides is crucial in biological processes.
• Neurotoxic peptide oligomerization is often induced by metal ions.
• Direct observation of metal-induced peptide oligomerization by mass spectrometry is rare.

Purpose of the Study:

• To investigate copper(II) ion binding with tetraglycine peptide (Gly-Gly-Gly-Gly).
• To explore metal ion-induced peptide aggregation and oligomerization mechanisms.
• To demonstrate the utility of mass spectrometry in observing these phenomena.

Main Methods:

• Electrospray ionization mass spectrometry (ESI-MS).
• Experiments conducted under alkaline conditions (pH 10.95) with ethanolamine.
• Analysis of peptide-copper(II) ion interactions at various ratios.

Main Results:

• Copper(II) ions induced aggregation of tetraglycine peptide.
• Formation of higher molecular mass copper-bound oligomer complexes, e.g., [3M+2Cu-3H](+) and [4M+3Cu-5H](+).
• The singly charged [3M+2Cu-3H](+) oligomer complex was the base peak at a 1:1 peptide-copper(II) ion ratio.

Conclusions:

• Short peptides can serve as models for studying metal ion binding.
• Mass spectrometry is a valuable tool for directly observing metal ion-induced peptide oligomerization.
• Findings contribute to understanding peptide-metal interactions and aggregation pathways.