What causes the Denaturing is the action of the heavy metal ions on specific groups of the protein enzyme itself which is described below
Heavy metals, such as lead (Pb) and mercury (Hg) exert their poisoning effect by binding to ionisable or sulfhydryl groups of proteins, including vital enzymes. Once they bind to an essential functional protein, such as an enzyme, they denature and/or inhibit it. *8
The sulfhyrdrl groups are mentioned in the primary structure of the Enzyme Amylase. The action of these bonding to the ions causes the denaturing of the enzyme.
From all of this information we can quite accurately make a prediction that the lead ions will more than likely have an inhibitory effect on the Amylase and the effect will be irreversible. As a result from the test I then believe that the higher the concentration of the lead nitrate solution the longer it takes for the enzymes to fully react the starch solution. I also believe that the effect of the lead ions (time taken for starch to react) is proportional to the concentration i.e. if we double the concentration the time taken will approximately double also. …
