Photodegradation
Definition
Breakdown of biological molecules driven by ultraviolet and visible radiation. In bloodstains it accelerates haemoglobin oxidation and cleaves DNA strands, hastening ageing of both colour and DNA yield.
Related terms
- Haemichrome
- A further oxidation product formed when the globin chains of methaemoglobin denature and the haem group becomes internally coordinated. Associated with the...
- Methaemoglobin
- An oxidised form of haemoglobin in which ferrous iron (Fe2+) is converted to ferric iron (Fe3+), unable to carry oxygen. Its formation...
- Oxyhaemoglobin
- The form of haemoglobin in freshly shed arterial blood, where iron in the haem group is in the ferrous (Fe²⁺) state and...
- Protein denaturation
- Unfolding and cross-linking of protein structure under heat, desiccation, or chemical stress. Affects haemoglobin, albumin, and other blood proteins as a stain...
- Substrate effect
- The influence of the surface on which a bloodstain lies on the rate and character of chemical change. Porous substrates absorb blood...
Explained in
- Physical and Chemical Changes in Ageing BloodstainsBreakdown of biological molecules driven by ultraviolet and visible radiation. In bloodstains it accelerates haemoglobin oxidation and cleaves DNA strands, has...