Denaturation: After death, the biological structures that maintain protein conformation break down, causing proteins to lose their native structure and become denatured. This process makes proteins more susceptible to chemical changes and enzymatic degradation.
Proteolysis: Enzymes called proteases, which are present in the tissues of the dead organism and produced by microorganisms, begin to break down proteins into smaller peptides and amino acids. This process is known as proteolysis.
Autolysis: Autolysis is the self-digestion of tissues due to the release of endogenous enzymes from within the cells. These enzymes degrade cellular components, including proteins, into smaller molecules.
Bacterial Decomposition: Bacteria and other microorganisms present in the environment contribute to the decomposition of proteins. They produce various enzymes that can break down proteins and utilize them as a source of nutrients. Bacterial decomposition leads to the formation of a range of products, including amino acids, peptides, and ammonia.
Putrefaction: Putrefaction is the breakdown of proteins by certain bacteria that produce foul-smelling compounds such as hydrogen sulfide, ammonia, and amines. This process is often associated with the decomposition of animal carcasses.
Deamination: Deamination is the removal of amino groups from amino acids. It can occur through enzymatic reactions or non-enzymatic processes. Deamination results in the release of ammonia and the formation of keto acids.
Decarboxylation: Decarboxylation is the removal of carboxyl groups from amino acids. It is typically catalyzed by enzymes known as decarboxylases. Decarboxylation leads to the production of amines and carbon dioxide.
Formation of Advanced Glycation End Products (AGEs): Over time, proteins can undergo non-enzymatic reactions with sugars, leading to the formation of AGEs. AGEs are stable compounds that accumulate in tissues and are implicated in aging and various diseases.
These chemical changes result in the breakdown of proteins and the release of simpler nitrogenous compounds and other molecules. The process of decomposition eventually leads to the recycling of nutrients back into the environment, contributing to the biogeochemical cycles of elements.