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Peptide Inhibitor of Complement C1 (PIC1) demonstrates antioxidant activity via single electron transport (SET) and

Magdielis Gregory Rivera1, Pamela S Hair2, Kenji M Cunnion1,2,3,4

  • 1Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, Virginia, United States of America.

Plos One
|March 3, 2018
PubMed

Insights

Peptide Inhibitor of Complement C1 (PIC1) demonstrates significant in vitro antioxidant activity by neutralizing reactive oxygen species (ROS). This peptide utilizes both single electron transfer and hydrogen atom transfer mechanisms, offering a novel therapeutic avenue.

Area of Science:

  • Biochemistry
  • Immunology
  • Molecular Biology

Background:

  • Reactive oxygen species (ROS) pose a threat to organs and tissues.
  • Antioxidant systems can be overwhelmed in pathological conditions.
  • Peptide Inhibitor of Complement C1 (PIC1) was previously shown to mitigate peroxidase activity of heme proteins.

Purpose of the Study:

  • To investigate the antioxidant properties of Peptide Inhibitor of Complement C1 (PIC1).
  • To elucidate the mechanisms underlying PIC1's antioxidant activity.
  • To assess PIC1's potential as an antioxidant agent.

Main Methods:

  • PIC1 was evaluated using established antioxidant assays: Total Antioxidant Capacity (TAC), Hydroxyl Radical Antioxidant Capacity (HORAC), Oxygen Radical Antioxidant Capacity (ORAC), and Thiobarbituric Acid Reactive Substances (TBARS).
  • Mechanisms of action were assessed through TAC and HORAC/ORAC assays.
  • The role of cysteine residues was investigated by assessing antioxidant activity after oxidation.

Main Results:

  • PIC1 exhibited dose-dependent antioxidant activity across multiple assays.
  • PIC1 functions via single electron transfer (SET) and hydrogen atom transfer (HAT) mechanisms.
  • Oxidation of PIC1's cysteine residues significantly reduced its antioxidant capacity, highlighting their importance.

Conclusions:

  • Peptide Inhibitor of Complement C1 (PIC1) possesses significant in vitro antioxidant activity.
  • PIC1's antioxidant effects are mediated by its cysteine residues and operate through SET and HAT pathways.
  • PIC1 represents a potential therapeutic agent for conditions involving oxidative stress, in addition to its complement-inhibiting role.

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