Abstract: Animal defensins is a kind of antibacterial cationic peptides that contains Cysteine-rich and Disulfide Bridge. They have broad activity spectra and special functional mechanisms, and play an important role of killing bacteria, anticancer, anti-HIV, transgenic and food engineering. This review focuses on its distributing, molecular structure, gene mapping ,genetic evolution,biological activity and mechanisms, and also the expression and regulation of the defensin genes. 

Key words: defensins; antibacterial cationic peptides; gene mapping; transgene engineering