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防御素是一类富含半胱氨酸的阳离子短肽,脊椎动物、无脊椎动物和植物中均有发现,在机体对抗细菌、真菌、原虫和病毒的先天免疫中发挥作用。哺乳动物防御素主要表达于皮肤、呼吸道、胃肠道和泌尿生殖道的上皮细胞,形成屏障以对抗外部感染因子[1]。此外在白细胞(主要是嗜中性粒细胞)也有表达,杀死已经侵入体内的微生物[2]。成熟的防御素含有6个半胱氨酸残基(Cys1~6),形成3个分子内二硫键,根据连接方式的不同分为α、β和θ防御素。
Defensins are a class of short cysteine-rich cationic peptides found in vertebrates, invertebrates and plants and play a role in the body’s innate immunity against bacteria, fungi, protozoa and viruses. Mammalian defensins are mainly expressed on the epithelial cells of the skin, respiratory, gastrointestinal and genitourinary tract, forming a barrier against external infectious agents [1]. In addition, leukocytes (mainly neutrophils) are also expressed to kill microorganisms that have invaded the body [2]. Mature defensins contain 6 cysteine residues (Cys1 ~ 6), forming three intramolecular disulfide bonds, which are classified into α, β and θ defensins depending on the mode of attachment.