Proteolysis
Definition
The hydrolytic cleavage of peptide bonds by proteolytic enzymes (proteases). In biological evidence, proteolysis occurs via endogenous cellular proteases released during autolysis and via exogenous microbial proteases. Proteolysis fragments proteins and can co-degrade DNA-binding proteins, accelerating overall evidence degradation.
- Mechanism
- Hydrolytic cleavage of peptide bonds
- Endogenous source
- Cellular proteases released during autolysis
- Exogenous source
- Microbial proteases
- Downstream effect
- Can co-degrade DNA-binding proteins, speeding DNA loss
Common questions
Why does proteolysis matter for DNA recovery from degraded evidence?+
Histones and other DNA-binding proteins normally protect genomic DNA from nuclease attack; once proteases break these proteins down, the exposed DNA becomes more vulnerable to fragmentation, which is one reason old or badly stored biological evidence often yields poor-quality profiles.
Does proteolysis proceed at the same rate in all biological evidence?+
No. Rate depends heavily on temperature, moisture, and microbial load, so a bloodstain kept cool and dry proteolyzes far more slowly than the same stain in warm, humid conditions where bacterial protease activity accelerates rapidly.
Related terms
- Amino Acid
- The monomer unit of proteins. All 20 standard amino acids share a central carbon bonded to an amino group, a carboxyl group,...
- Haemoglobin
- The iron-containing oxygen-transport protein in red blood cells, composed of four polypeptide subunits each with a haem prosthetic group. Its pseudoperoxidase activity...
- Isoenzyme (Isozyme)
- Multiple molecular forms of the same enzyme that differ in amino acid sequence but catalyse the same reaction. In forensic serology, isoenzyme...
- Peroxidase
- An enzyme that catalyses the transfer of oxygen from hydrogen peroxide to an electron donor, often producing a coloured product. Haemoglobin has...
- Protein Denaturation
- The loss of a protein's three-dimensional structure without breaking peptide bonds, caused by heat, pH change, UV radiation, or chemical agents such...