|
|Section2= |Section3= }} Melittin is the principal active component of apitoxin (bee venom) and is a powerful stimulator of phospholipase A2. Melittin is a peptide consisting of 26 amino acids with the sequence GIGAVLKVLTTGLPALISWIKRKRQQ. == Biological effects == Melittin inhibits protein kinase C, Ca2+/calmodulin-dependent protein kinase II, myosin light chain kinase and Na+/K+-ATPase (synaptosomal membrane) and is a cell membrane lytic factor. Melittin is a small peptide with no disulphide bridge; the N-terminal part of the molecule is predominantly hydrophobic and the C-terminal part is hydrophilic and strongly basic. Extensive work with melittin has shown that the venom has multiple effects, probably, as a result of its interaction with negatively charged phospholipids. It inhibits well known transport pumps such as the Na+-K+-ATPase and the H+-K+-ATPase. Melittin increases the permeability of cell membranes to ions, particularly Na+ and indirectly Ca2+, because of the Na+-Ca2+-exchange. This effect results in marked morphological and functional changes, particularly in excitable tissues such as cardiac myocytes. In some other tissues, e.g., cornea, not only Na+ but Cl− permeability is also increased by melittin. Similar effects to melittin on H+-K+-ATPase have been found with the synthetic amphipathic polypeptide Trp-3. Melittin also exhibits potent anti-microbial activity. For example, melittin has been shown to exert "profound inhibitory effects" on ''Borrelia burgdorferi'', the bacteria that causes lyme disease. Melittin has also been shown to kill the yeast ''Candida albicans'' and to suppress ''Mycoplasma hominis'' and ''Chlamydia trachomatis'' infections. 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「Melittin」の詳細全文を読む スポンサード リンク
|