Defensins are peptides that contain a large number of cysteine in the sequence. They are widely distributed in fungi, plants and animals, and play an important regulatory role in the biological immune system. Defensins have a direct bactericidal function and are an important class of antibacterial peptides. α-Defensin 6 is composed of 32 amino acids, the sequence contains 6 cysteines, and is positioned to form 3 pairs of disulfide bonds. The secondary structure is more stable and has a longer half-life.