Question

Calculating the Molecular Weight and Subunit Organization of a Protein From Its Metal Content The element molybdenum (atomic weight 95.95) constitutes 0.08% of the weight of nitrate reductase. If the molecular weight of nitrate reductase is 240,000, what is its likely quaternary structure?

Answer 1

Answer:

Dimer of two peptide chains with 1 mole of molybdenum metal each.

Explanation:

Percentage of molybdenum in protein = 0.08%

Molecular mass of nitrate reductase = 240,000 g

Mass of molybdenum = x

$0.08\%=\frac{x}{240,000 g}\times 100=192 g$

Moles of molybdenum =$\frac{192 g}{95.95 g/mol}=2.00 mol$

Each peptide chain of nitrate reductase contain 1 mole of molybdenum.

This means that nitrate reductase is composed of to two peptide chains. And in each peptide there is a single mole of molybdenum metal.