Ceratotoxin

Ceratotoxins are short linear cationic antibacterial peptides that are produced in the female reproductive accessory glands of the medfly Ceratitis capitata. Bacterial infection has no effect on their expression, which is instead increased upon mating and regulated by juvenile hormone.

In 1993, ceratotoxin peptides initially were isolated from the secretion of the female reproductive accessory glands of the dipteran insect Ceratitis capitata. Ceratotoxins exhibits strong antibacterial activity, and three distinct ceratotoxins-Ceratotoxins A, B, and C-have completed purification. The length of all three ceratotoxins is 29 amino acids, with two amino acids differing at positions 6 and 19. They are both heat stable and highly basic. Their polar amino acids lying parallel to their alpha-helices, making them all amphiphilic.

Owing to their amphiphilic property, ceratotoxins has antibacterial nature. Ceratotoxins has been shown to be effectively against both gram negative and gram positive bacteria. By binding to the cell membrane, they establish voltage-dependent ion channels that destroy the bacteria. Ceratotoxins, which main function is to protect the genital tract from bacterial infections during fertilization, are mostly expressed by an adult female insect.