Muta T, Fujimoto T, Nakajima H, Iwanaga S
Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Fukuoka.
J Biochem. 1990 Aug;108(2):261-6. doi: 10.1093/oxfordjournals.jbchem.a123191.
Tachyplesins and their analogs are antimicrobial peptides composed of 17 or 18 amino acid residues present abundantly in acid extracts of hemocyte debris of horseshoe crabs. We purified here tachyplesin isopeptides from hemocytes of two species of Southeast Asian horseshoe crabs, Carcinoscorpius rotundicauda and Tachypleus gigas, and determined their amino acid sequences. The major tachyplesin isolated from both species was identified, respectively, as tachyplesin I, which had previously been found in hemocytes of the Japanese horseshoe crab (Tachypleus tridentatus). The yield from both species was very high (more than 70 mg per 100 g wet weight of hemocytes), i.e., comparable with that from T. tridentatus. In addition to tachyplesin I, a new tachyplesin isopeptide, named tachyplesin III, was also isolated from T. gigas hemocytes, in which an arginine replaced the 15th lysine of tachyplesin I. The carboxyl-terminal residue of the isolated tachyplesins I and III was confirmed, respectively, to be an arginine alpha-amide by chemical analysis. Furthermore, a tachyplesin peptide derivative with a carboxyl-terminal extension of glycine-lysine was newly found in the hemocytes of C. rotundicauda. It appeared to be an intermediate derived from a tachyplesin precursor during processing to the mature form.
鲎素及其类似物是由17或18个氨基酸残基组成的抗菌肽，大量存在于鲎血细胞碎片的酸性提取物中。我们从两种东南亚鲎（圆尾鲎和巨鲎）的血细胞中纯化了鲎素异肽，并确定了它们的氨基酸序列。从这两种鲎中分离出的主要鲎素分别被鉴定为鲎素I，它此前已在日本鲎（三刺鲎）的血细胞中被发现。这两种鲎的产量都非常高（每100克湿重的血细胞中超过70毫克），即与三刺鲎的产量相当。除了鲎素I，还从巨鲎的血细胞中分离出一种新的鲎素异肽，命名为鲎素III，其中一个精氨酸取代了鲎素I的第15位赖氨酸。通过化学分析分别证实了分离出的鲎素I和III的羧基末端残基为精氨酸α-酰胺。此外，在圆尾鲎的血细胞中新发现了一种羧基末端延伸有甘氨酸-赖氨酸的鲎素肽衍生物。它似乎是鲎素前体在加工成成熟形式过程中衍生出的一种中间体。
