Forensic Chemistry > 3. Because proteins are a major structural and metabolic component of all living organisms, the analysis of protein samples can be useful in forensic chemistry > The Peptide Bond >
Describe the nature of the peptide bond and explain that proteins can be broken at different lengths in the chain by choice of enzyme
Nature of Peptide Bond
- Is an amide bond that connects amino acids to form polypeptide or protein
- Peptide bonds present in protein sequence can be cleaved by at different lengths in the chain via hydrolysis
- Acid and Base Hydrolysis
- Polypeptide chain is broken down into its constituent amino acids using strong acid (HCl) and base (NaOH)
- Disadvantage: Causes destruction of some amino acids
- Hydrolysis by Enzymes
- Selected peptide bond in the protein is cleaved resulting to varying length of peptide fragments
- Examples of enzymes used for cleaving proteins into peptides are:
- Pepsin – digestive enzyme; cleaves peptide bonds involving the amino side of aromatic amino acids and acidic amino acids
- Chymotrypsin – digestive enzyme; involves in cleaving the peptide bond in the carboxyl side of aromatic amino acids
- Trypsin – digestive enzyme; involves in cleaving the peptide bond in the carboxyl side of basic amino acids