Singlet oxygen‐induced protein aggregation: Lysozyme crosslink formation and nLC‐MS/MS characterization

Abstract

Singlet molecular oxygen ( 1 O 2 ) has been associated with a number of physiological processes. Despite the recognized importance of 1 O 2 -mediated protein modifications, little is known about the role of this oxidant in crosslink formation and protein aggregation. Thus, using lysozyme as a model, the present study sought to investigate the involvement of 1 O 2 in crosslink formation. Lysozyme was photochemically oxidized in the presence of rose bengal or chemically oxidized using [ 18 O]-labeled 1 O 2 released from thermolabile endoperoxides. It was concluded that both 1 O 2 generating systems induce lysozyme crosslinking and aggregation. Using SDS-PAGE and nanoscale liquid chromatography coupled to electrospray ionization mass spectrometry, the results clearly demonstrated that 1 O 2 is directly involved in the formation of covalent crosslinks involving the amino acids histidine, lysine, and tryptophan.

Catalytic photooxygenation degrades brain Aβ in vivo

“…Oxidative dimerization (and oligomerization) of peptides through cross-linking between oxidized His and nucleophilic amino acid residues such as Lys or His was previously reported (Fig. 5C) (30)(31)(32)(33). Accordingly, catalyst 7 photooxygenated A present in low concentrations in brain lysate containing a large number of off-target molecules.…”

A Photosensitized Singlet Oxygen (1O2) Toolbox for Bio-Organic Applications: Tailoring 1O2 Generation for DNA and Protein Labelling, Targeting and Biosensing

“…Recently, E. F. Marques et al proved, using mass spectrometry, that 2′ oxo-histidine can react with Trp, Lys or other His residues, leading to cross-link formation and aggregation in lysozyme. Additionally, it was shown that oxidized forms of tryptophan could cross-link to histidine or to other tryptophan moieties [ 46 ]. Additionally, S. Jiang et al described a novel disulphide CL pathway, based on the photo-oxidation of disulphide bonds, which leads to reactive intermediates that on their turn give rise to new protein–protein cross-links ( vide infra Section 3.1.2 ) [ 47 ].…”

“…It was proven that 1 O 2 was involved in the generation of cross-links between oxidized histidine, histidine, lysine and kynurenine derivative of trypthophan. Additionally, cross-links between oxidized trypthophan and the open ring kynurenine derivative were seen [ 46 ]. A small overview on the types of protein cross-links and high molecular mass aggregates is given by E. Fuentes-Lemus et al, combined with the relation of photo-oxidation of protein with pathological conditions [ 137 ].…”

“…( B ) Proposed mechanistic pathway for the glutathione conjugation onto oxidized tyrosine residues in peptides and proteins, further elaborated in [ 129 ]. ( C ) Proposed intermolecular lysozyme cross-links after 1 O 2 -mediated oxidation of histidine and tryptophan, introduced in [ 46 ]. ( D ) 1 O 2 -mediated peptide–peptide ligation method, shown in [ 106 ].…”

The Reactive Oxygen Species Singlet Oxygen, Hydroxy Radicals, and the Superoxide Radical Anion—Examples of Their Roles in Biology and Medicine

“…Di Mascio and co-workers have studied the generation of singlet oxygen ( 1 O 2 ) in biological systems-see, for example, [4]-showing the generation of 1 O 2 from lipid hydroperoxides and nitronium ions. This group has also shown that 1 O 2 is involved in the formation of covalent crosslinks involving histidine, lysine, and tryptophan [5].…”