# Molecular Aspects of Methylcadmium Toxicity: Effects on the H2O2 Reduction by Cysteine and Selenocysteine Disclosed In Silico

## TL;DR

This paper explores how methylcadmium causes toxicity by disrupting antioxidant enzymes, similar to methylmercury.

## Contribution

The study reveals methylcadmium's pro-oxidant effects and its interaction with selenocysteine and antioxidant enzymes using computational methods.

## Key findings

- Methylcadmium binds to GPx1 and TrxR1 enzymes, potentially inhibiting their activity.
- Methylcadmium's pro-oxidant activity is nearly as strong as methylmercury's.
- Selenocysteine may be a target for methylcadmium's toxic effects.

## Abstract

Cadmium (Cd), like the other group 12 elements (Zn and
Hg), has
a high affinity for sulfur (S) and selenium (Se), a property that
strongly influences its adverse biological effects. Although the symptoms
of Cd toxicity are diverse, a common denominator is found in oxidative
stress, resulting in the disruption of redox balance in cells and
the proliferation of reactive oxygen species (ROS) and harmful radicals.
Methylcadmium (CH3Cd+) is a convenient model
to study Cd pro-oxidant activity in silico. In this work, the effect
of CH3Cd+ on the peroxy-reducing potential of
cysteine (Cys) and selenocysteine (Sec) is investigated at the ZORA-BLYP-D3­(BJ)/TZ2P
level and compared to our current knowledge on the analogous molecular
aspects of methylmercury’s toxicity (CH3Hg+). Molecular docking simulations indicate that CH3Cd+ binds favorably to the catalytic sites of the GPx1 and TrxR1
enzymes. The short distances between the metal and Sec suggest that
a nucleophilic attack by Se to Cd leading to the inhibition of the
enzyme is indeed possible. Methylcadmium pro-oxidant activity isif
not equalonly slightly inferior to that of methylmercury.