Plasma protein fraction: the disappearance of kinin from the solution on storage

The kinin produced when plasma protein fraction was heated at 60 C for 10 hours in order to inactivate the agent of hepatitis was shown to lose its activity during storage. There was an 80 per cent loss after three months and negligible activity was detectable after six months of storage. Synthetic bradykinin treated and stored under the same conditions showed no loss in activity.