| Name | Half-Life |
|---|---|
| Collagen | 117 years |
| Eye lenscrystallin | >70 years |
| RFC1 | 9 hours |
| RPS8 | 3 hours |
| Ornithine decarboxylase | 11 minutes |
Incell biology,protein turnover refers to the replacement of olderproteins as they arebroken down within thecell. Different types of proteins have very different turnover rates.
A balance betweenprotein synthesis andprotein degradation is required for good health and normal protein metabolism. More synthesis than breakdown indicates ananabolic state that builds lean tissues, more breakdown than synthesis indicates acatabolic state that burnslean tissues. According to D.S. Dunlop, protein turnover occurs inbrain cells the same as any othereukaryotic cells, but that "knowledge of those aspects of control and regulation specific or peculiar to brain is an essential element for understanding brain function."[3]
Protein turnover is believed to decrease with age in allsenescent organisms including humans. This results in an increase in the amount of damaged protein within the body.
Four weeks ofaerobic exercise has been shown to increase skeletal muscle protein turnover in previously unfit individuals.[4] A diet high in protein increases whole body turnover in endurance athletes.[5][6]
Somebodybuilding supplements claim to reduce the protein breakdown by reducing or blocking the number of catabolic hormones within the body. This is believed to increase anabolism. However, if protein breakdown falls too low then the body would not be able to remove muscle cells that have been damaged during workouts which would in turn prevent the growth of new muscle cells.
