Photoinactivation of ichthyotoxin from axenic cultures of Prymnesium parvum Carter.

The ichthyotoxin of Prymnesium parvum is inactivated by visible (400 to 510 mmu) as well as by ultraviolet light (255 mmu). The changes in the absorption spectrum of purified (pigment-free) ichthyotoxin during this process indicate that different mechanisms may be involved in the inactivation by visible or ultraviolet light. Photoinactivation is not affected by the presence of cells, cell pigments, oxygen, or glutathione.