Multiple Choice
In biochemistry, what is a peptide bond?
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4. Protein Structure
Peptide Bond
Multiple Choice
In proteins, how are peptide bonds formed between two amino acids?
A
By hydrolysis of an existing amide bond, consuming to link the amino acids
B
By a condensation (dehydration) reaction between the carboxyl group of one amino acid and the amino group of another, releasing
C
By an oxidation reaction that creates a disulfide bond between two cysteine side chains
D
By formation of an ionic (salt) bridge between the amino and carboxyl groups without loss of any small molecule
Verified step by step guidance1
Identify the functional groups involved in peptide bond formation: the carboxyl group (-COOH) of one amino acid and the amino group (-NH2) of another amino acid.
Understand that peptide bonds are formed through a condensation (dehydration) reaction, which means a molecule of water (H\_2O) is released during the process.
Write the general reaction where the hydroxyl group (-OH) from the carboxyl group and a hydrogen atom (H) from the amino group are removed to form water:
\[ \mathrm{R_1{-}COOH} + \mathrm{H_2N{-}R_2} \rightarrow \mathrm{R_1{-}CO{-}NH{-}R_2} + H_2O \]
Recognize that the bond formed between the carbon atom of the carboxyl group and the nitrogen atom of the amino group is called a peptide bond (an amide bond).
Note that this process is not hydrolysis (which breaks peptide bonds by adding water), nor is it an oxidation or ionic interaction; it specifically involves the removal of water to link amino acids covalently.
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