Nickel (II) as a temporary catalyst for hydroxyl radical generation

Area of Science:

• Biochemistry
• Toxicology
• Chemical Biology

Background:

• Nickel toxicity is linked to oxidative stress and oxygen-activated species generation.
• Histidylpeptides-Ni (II) complexes are investigated for their potential role in catalyzing reactive oxygen species (ROS) production.

Purpose of the Study:

• To determine if histidylpeptides-Ni (II) complexes catalyze nickel-dependent hydrogen peroxide reduction and free oxygen radical production.
• To elucidate the mechanism of nickel-induced oxidative damage involving specific peptide sequences.

Main Methods:

• Utilized the murexide bleaching technique for spectroscopic analysis.
• Investigated the effects of glycyl-glycyl-L-histidyl peptides on hydrogen peroxide reduction and radical generation in the presence of Ni (II).
• Assessed protein damage, tryptophan degradation, bityrosine formation, and polyunsaturated fatty acid peroxidation.

Main Results:

• Peptides with the glycyl-glycyl-L-histidyl sequence were shown to trigger nickel-dependent oxygen radical production.
• These oxygen radicals induced protein damage, tryptophan loss, bityrosine formation, and polyunsaturated fatty acid peroxidation.
• Selective damage to the histidine residue within the peptide was observed, leading to the cessation of hydroxyl radical production upon peptide breakdown.

Conclusions:

• Specific histidylpeptides can mediate nickel-induced oxidative stress by catalyzing ROS production.
• The mechanism involves the nickel-dependent reduction of hydrogen peroxide, leading to significant biomolecular damage.
• Peptide degradation, specifically histidine modification, acts as a self-limiting mechanism for radical production.