Effect of protein structure and/or conformation on the dityrosine cross-linking induced by haem-hydrogen peroxide

• Published in: Biochimica et biophysica acta Vol. 1860; no. 10; pp. 2232 - 2238
• Main Authors: Ke, Zhigang, Huang, Qing
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.10.2016
• Subjects: absorbance; circular dichroism spectroscopy; Cross-linking; Cross-Linking Reagents; crosslinking; Dimerization; Dityrosine; electron paramagnetic resonance spectroscopy; Electron Spin Resonance Spectroscopy; Electrophoresis, Polyacrylamide Gel; fluorescence; Hematin; Heme - chemistry; Heme - metabolism; Hemin - chemistry; Humans; hydrogen peroxide; Hydrogen Peroxide - chemistry; neurodegenerative diseases; Oxidation-Reduction - drug effects; oxidative stress; Oxidative Stress - drug effects; polyacrylamide gel electrophoresis; Protein Aggregates; Protein Conformation - drug effects; Protein structure; proteins; Raman spectroscopy; Spectrum Analysis, Raman; Structural effect; tissues; toxicity; Tyrosine - analogs & derivatives; Tyrosine - chemistry; Structural effect; Dityrosine; Cross-linking; Protein structure; Hematin
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/j.bbagen.2016.04.023

Haem, an essential cofactor in aerobic organisms, can cause oxidative stress and impose toxic effects on tissues and organs. It can induce aggregation of proteins via dityrosine cross-linking and cause neurodegenerative diseases. Although dityrosine cross-linking in many proteins induced by haem has been reported, not all the proteins have the same effect or the efficiency of cross-linking varies, while the reason has not been clarified. The correlation of protein structure/conformation with its aggregation tendency via dityrosine induced by hematin (oxidized form of haem) in the presence of hydrogen peroxide (H2O2) was studied through reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), fluorescence and circular dichroism (CD) measurements, and the mechanism was investigated by performing UV–Vis absorbance, Raman spectroscopy and low-temperature electron spin resonance (ESR) experiments. It was found that proteins in unstructured state are more readily to be cross-linked via dityrosine formation by hematin-H2O2. The unstructured protein without steric effect can coordinate with hematin to form six-coordinated protein-hematin complex, in which the produced tyrosyl radicals by H2O2 are with high tendency to dimerize to form dityrosine. Our results demonstrate that protein structure/conformation can affect its coordination state with haem, and the tendency of reaction of two tyrosyl radicals, further influencing the yield and efficiency of dityrosine cross-linking in the presence of H2O2. This research can help to deepen our understanding of the protein aggregation and inactivation mechanisms in varied sophisticated conditions, and especially give us the new insight into the toxic effects under haem stress. [Display omitted] •The efficiency of hematin-H2O2 induced dityrosine cross-linking depends on protein structure and/or conformation.•The steric effect is correlated to haem coordination and tyrosyl radical formation inside the proteins.•The mechanism was revealed by application of various spectroscopic tools.