<unk> s are a family of mammalian<unk>  peptides of the<unk>  subfamily. In mammals they are also known as cryptdins and are produced within the small bowel. Cryptdin is a portmanteau of crypt and<unk> .<unk> s are 2-6 kDa, cationic, microbicidal peptides active against many Gram-negative and Gram-positive bacteria, fungi, and enveloped viruses, containing three pairs of intramolecular disulfide bonds. On the basis of their size and pattern of disulfide bonding, mammalian<unk> s are classified into<unk> , beta and theta categories.<unk> s, which have been identified in humans, monkeys and several rodent species, are particularly abundant in neutrophils, certain macrophage populations and Paneth cells of the small intestine.<unk> s are produced constitutively and/or in response to microbial products or proinflammatory cytokines. Some<unk> s are also called corticostatins (CS) because they inhibit corticotropin-stimulated corticosteroid production. The mechanism(s) by which microorganisms are killed and/or inactivated by<unk> s is not understood completely. However, it is generally believed that killing is a consequence of disruption of the microbial membrane. The polar topology of<unk> s, with spatially separated charged and hydrophobic regions, allows them to insert themselves into the phospholipid membranes so that their hydrophobic regions are buried within the lipid membrane interior and their charged (mostly cationic) regions interact with anionic phospholipid head groups and water. Subsequently, some<unk> s can aggregate to form 'channel-like' pores; others might bind to and cover the microbial membrane in a 'carpet-like' manner. The net outcome is the disruption of membrane integrity and function, which ultimately leads to the lysis of microorganisms. Some<unk> s are synthesized as propeptides which may be relevant to this process.<unk> s of the mouse bowel were historically called cryptdins when first discovered.
Alpha defensin
Beta defensin
Defensin
Immunoevasin
Neutrophil elastase
Leukotriene
Histamine
Major basic protein