Abstract: Defensins are found in recent years a class of broad-spectrum anti-microbial activity of cationic peptides from 38 to 100 amino acid residues and intramolecular disulfide bond rich in natural immunity and acquired immunity play important role, because of its strong molecular skeleton, a broad distribution and biological activity of the above research and development of its medicinal value, for the people an alternative to traditional antibiotics provides a new way. This paper describes the structural features of defensins and function, distribution, biological activity, peptide analog design and application.

Key words: defensins; structure and function; biological activity; design of analog peptides