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Effects of some metals on paraoxonase activity from shark Scyliorhinus canicula

Demet Sayın1, Dilek Türker Cakır, Nahit Gençer

  • 1Department of Chemistry, Science and Art Faculty, Cagis Yerleskesi, Balikesir University, Balikesir, Turkey.

Journal of Enzyme Inhibition and Medicinal Chemistry
|September 3, 2011
PubMed

Insights

Investigating metal ion toxicity, this study found that nickel, cadmium, copper, and mercury ions inhibit shark serum paraoxonase (SPON) enzyme activity. Copper ions were the most potent inhibitors, highlighting risks associated with heavy metal exposure.

Area of Science:

  • Biochemistry
  • Enzymology
  • Environmental Toxicology

Background:

  • Paraoxonase (PON) is a vital enzyme with organophosphate hydrolyzing and antioxidant functions.
  • Enzyme activity is crucial and should not be altered; inhibition can be dangerous.
  • Metal ion toxicology on enzymes is an emerging area of research.

Purpose of the Study:

  • To investigate the in vitro inhibitory effects of specific metal ions on shark serum paraoxonase (SPON) activity.
  • To determine the inhibitory potential of Ni(2+), Cd(2+), Cu(2+), and Hg(2+) on SPON.

Main Methods:

  • Purification of shark serum paraoxonase (SPON) from Scyliorhinus canicula serum.
  • Analysis of SPON activity in the presence of varying concentrations of metal ions (Ni2+, Cd2+, Cu2+, Hg2+).
  • Determination of enzyme kinetics (K(M), V(max)) and inhibitory parameters (IC(50)).

Main Results:

  • All tested metal ions (Ni2+, Cd2+, Cu2+, Hg2+) demonstrated inhibitory effects on SPON activity at low concentrations.
  • The IC(50) values for the metal ions ranged from 0.29 to 2.00 mM.
  • Copper (Cu2+) exhibited the strongest inhibitory effect, with an IC(50) of 0.29 mM.

Conclusions:

  • Metal ions, particularly copper, can significantly inhibit shark serum paraoxonase activity in vitro.
  • These findings underscore the potential toxicological impact of heavy metals on essential enzyme functions.
  • Further research into metal-enzyme interactions is warranted to understand broader physiological implications.

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