Isolation and purification of a neurodepressing hormone from the eyestalk of Procambarus bouvieri (Ortmann).

1. A neurodepressing hormone has been isolated and purified to homogeneity from aqueous extracts of 2000 eyestalks of the Mexican crayfish Procambarus bouvieri (Ortmann). 2. Purification was achieved by gel filtration on Sephadex G-25 and G-15, and preparative paper electrophoresis at four pH valueimately 1200 molecular weight and composed of neutral amino acids. 5. No N-terminal group could be found. From its electrophoretic behavior it is concluded that the C-terminal group is also blocked.