The molecular formula for the amino acid lysine is C6H14N2O2.

Question

The molecular formula for the amino acid lysine is C₆H₁₄N₂O₂. What would be the molecular formula for a polypeptide consisting of five lysine molecules?

Answer 1

Hi Harmani V.!

Forming a peptide bond is done by dehydration synthesis. It is a type of condensation reaction. Specifically, a peptide bond is an amide bond, and is a bond formed between the α-nitrogen of one amino acid and the carboxyl of a second residue. Each peptide bond formed involves the loss of one molecule of water.

In the case of a small polypeptide formed from the condensation of 5 lysine residues, we would require 4 peptide (amide) bonds holding it together. One molecule of water is lost during the formation of each of these bonds. This means we cannot simply multiple each subscript by 5. We must also account for the hydrogens and oxygens lost due to the formation of water. Therefore, our molecular formula is:

C₃₀H₆₂N₁₀O₆

Hope this helps!

Cheers

Answer 2

(C₆H₁₄N₂O₂)₅