Hg$^{2+}$ ions are toxic for several reasons. One reason is that Hg$^{2+}$ ions can react with the $\text{R-S-S-R}$ group found in proteins. $ \text{R-S-S-R} + 2\text{Hg}^{2+} + \text{H}_2 \rightarrow 2\text{R-S-Hg}^+ + 2\text{H}^+. $ What is the name of the $\text{R-S-S-R}$ group in proteins?
Which level of protein structure is changed by reaction 1?
Why does this reduce the activity of an enzyme?
Ag$^+$ ions can combine with free $\text{-COOH}$ groups in the side chains of amino acid residues in proteins, forming partially covalent silver carboxylates. $ \text{RCOOH} + \text{Ag}^+ \rightarrow \text{RCOOAg} + \text{H}^+. $ What kind of behaviour is the $\text{-COOH}$ group showing in reaction 2?
What kinds of R group interactions will be altered by reaction 2? Explain your answer.