柞蚕抗菌肽D中精氨酸、赖氨酸和色氨酸等氨基酸残基的化学修饰

STUDIES ON THE MODIFICATION OF ARGININE, LYSINE AND TRYPTOPHAN RESIDUES IN CECROPIN D FROM THE CHINESE OAK SILK MOTH, ANTHERAEA PERNYI

用不同的化学试剂修饰了柞蚕抗菌肽D分子中的色氨酸、精氨酸和赖氨酸等氨基酸残基。NBS修饰抗菌肽D,以及氨肽酶M对抗菌肽D作用的结果表明色氨酸残基对抗菌肽D抑制E.coli D31的作用影响不大。CHD和MLH对精氨酸和赖氨酸残基的修饰,导致抗菌肽D失去抑制E.coli的作用,但可逆地消除CHD和MLH的修饰作用后,抗菌肽D恢复了对E.coli D31的抑菌作用。这些结果初步认为,抗菌肽D抑菌作用与分子中的荷电性有关,改变了分子的电荷,也就同时失去了其抑菌功能。 此外,对精氨酸残基修饰的结果还表明,抗菌肽D的免疫原性与精氨酸残基有关。但是,抗菌肽D的免疫决定簇与其生物活性中心并不完全平行。

The tryptophan, arginine and lysinc residues of cecropin D were modified by N-bromosuccinimide (NBS), 1, 2 -cyclohexanedione ( CHD ) and maleic anhydride (MLH) respectively. It was found that the tryptophan residue bore little relationship to the antibacterial activity of the peptide against Escherichia coli D31, but that the arginine and lysine residues were important to the antibacterial activity. The modification of the arginine or lysine residue of cecropin D resulted in a total loss of its antibacterial activity against E. coli D31. When the arginine and lysine residues were each regenerated from the modified structures the antibacterial aciivity of cecropin D was recovered. These results suggest that the antibacterial activity of cecropin D is related to the charge in the molecule. Ouchterlony double immunodiffusion showed that the antigenic determinant of cecropin D is closely connected with the arginine residues in the peptide.