Metal ion Replacement in Manganoproteins:

Manganoproteins are proteins that contain manganese ions in their active site. These proteins are involved in various biochemical processes such as photosynthesis, respiration, and antioxidant defense. Sometimes, other metal ions can replace manganese ions in these proteins without changing their function.

Metal ion Replacement Options:

The metal ions that can replace manganese (II) ion in manganoproteins without changing its function are:

a) Fe (II)
b) Zn (II)
c) Mg (II)
d) Cu (II)

Correct Answer and Explanation:

The correct answer is option 'C' which is Mg (II). Magnesium ion is similar in size and electronic configuration to manganese ion, which makes it an ideal replacement. Moreover, magnesium ion is also biologically important and found in various enzymes and proteins.

Other Options Explanation:

a) Fe (II): Iron ion has a larger size and different electronic configuration than manganese ion, which makes it unsuitable for replacement. Moreover, iron ion is involved in various biological processes and can cause functional changes in manganoproteins.

b) Zn (II): Zinc ion is smaller in size than manganese ion and has a different electronic configuration, which makes it unsuitable for replacement. Moreover, zinc ion is involved in various biological processes and can cause functional changes in manganoproteins.

d) Cu (II): Copper ion has a different electronic configuration than manganese ion, which makes it unsuitable for replacement. Moreover, copper ion is involved in various biological processes and can cause functional changes in manganoproteins.