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Plant defensins (Formerly gamma-thionins) are a family of small, cysteine-rich proteins found in plants that serve to defend them against parasites. The following plant proteins belong to this family: * The flower-specific ''Nicotiana alata'' defensin (NaD1) * Gamma-thionins from ''Triticum aestivum'' (Wheat) endosperm (gamma-purothionins) and gamma-hordothionins from ''Hordeum vulgare''(Barley) are toxic to animal cells and inhibit protein synthesis in cell free systems. * A flower-specific thionin (FST) from ''Nicotiana tabacum'' (Common Tobacco). * Antifungal proteins (AFP) from the seeds of Brassicaceae species such as radish, mustard, turnip and ''Arabidopsis thaliana'' (Thale Cress). * Inhibitors of insect alpha-amylases from sorghum. * Probable protease inhibitor P322 from ''Solanum tuberosum'' (Potato). * A germination-related protein from ''Vigna unguiculata'' (Cowpea). * Anther-specific protein SF18 from sunflower. SF18 is a protein that contains a gamma-thionin domain at its N-terminus and a proline-rich C-terminal domain. * ''Glycine max'' (Soybean) sulfur-rich protein SE60. * ''Vicia faba'' (Broad bean) antibacterial peptides fabatin-1 and -2. In their mature form, these proteins generally consist of about 45 to 50 amino-acid residues. As shown in the following schematic representation, these peptides contain eight conserved cysteines involved in disulfide bonds. +-------------------------------------------+ | +-------------------+ | | | | | | | | | +---|----------------+ | +------------------+ 'C': conserved cysteine involved in a disulfide bond. The folded structure of Gamma-purothionin is characterised by a well-defined 3-stranded anti-parallel beta-sheet and a short alpha-helix.〔 Three disulfide bridges are located in the hydrophobic core between the helix and sheet, forming a cysteine-stabilised alpha-helical motif. This structure differs from that of the plant alpha- and beta-thionins, but is analogous to scorpion toxins and insect defensins. ==Databases== A database for antimicrobial peptides, including defensins is available: PhytAMP (http://phytamp.pfba-lab-tun.org). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Plant defensin」の詳細全文を読む スポンサード リンク
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