Fig. 6.

Method of antibacterial action of all discussed metals. M=metal. Silver releases small amounts of ions which can bind to and condense DNA, rendering it inaccessible for replication and susceptible to mutations. Silver can also inactivate cysteine residues on enzymes through their sulfhydryl groups, inhibiting enzymatic activity, and can target bacterial membranes, increasing permeability and reducing their stability. Gold inhibits the reducing activity of TrxR, increasing ROS and decreasing DNA replication and the formation of reduced disulfide bonds. As Ga(III), gallium acts as an iron mimetic, incorporating itself into iron-dependent enzymes. As Ga(III) cannot be reduced to Ga(II), it inhibits the activity of the enzyme. Copper promotes the production of ROS, which then cause damage to DNA as well as the bacterial membrane. Manganese promotes the production of ROS and binds and inactivates important biomolecules.