- Biological role of metallothioneins is to sequester harmful metal ions. These bind:
a) Cd++, Cu++ & Zn++
b) AI+++, Hg++ & NH4+
c) Pt++, As+++ & PO4–
d) Fe+++, Na+ & K+
Explanation:
Metallothioneins are the group of the small proteins found in the cytosol of the cells, particularly of liver, kidney and intestine.
They have a high content of cysteine and can bind copper, zinc, cadmium and mercury.
Important point:
The SH groups of cysteine are involved in binding of metals.
Answer: Cd++, Cu++ & Zn++
Ref: Harper 30th Ed. Page-