Abstract

Nowadays, an alarming increase in antibiotics resistance have steered intensive research to explore new substitutes for ineffective antibiotics. This study aimed (1) to identify the purified antibacterial peptide isolated from amoebocyte lysate of the Asian horseshoe crab, Tachypleus gigas, (2) to compare potency of antibacterial activity of the purified peptide in comparison to a commercial antibiotic (ampicillin), and (3) to evaluate thermostability and cytotoxicity of the purified peptide. Antibacterial peptide having molecular weight of 7.5 kDa and consisting of 10 amino acid sequence of SYFPGSTYGR at position of 54–63 was identified as tachystatin-A2. Peptide strongly inhibited the growth of 2 bacterial strains known as Escherichia coli ATCC 11775 and Bacillus subtilis ATCC 11774 with MIC values at 0.12 ± 0.09 and 0.12 ± 0.05 µg/mL, respectively. However, for Stapylococcus aureus, the potency of this antibacterial peptide was low, in which the activation only occurred at high concentration (IC₅₀ value = 15.63 ± 0.001 µg/mL). It was thermally stable when heated at 30, 50, 70 and 100°C. The testing cytotoxicity on the human liver cancer cell HepG2 line showed IC₅₀ value of 42.45 µg/mL indicating a non-toxic peptide. Based on its unique properties such as broad-spectrum activity, thermally stable, and non-toxic, the tachystatin-A2 has a huge potential as candidate for antibacterial product.

中文翻译：

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从亚洲马蹄蟹变形虫细胞中分离的纯化 Tachystatin-A2 作为潜在抗菌肽的表征

摘要

如今，抗生素耐药性的惊人增长促使深入研究探索无效抗生素的新替代品。本研究旨在 (1) 鉴定从亚洲鲎变形细胞裂解物中分离的纯化抗菌肽，Tachypleus gigas，(2) 比较纯化肽与商业抗生素（氨苄青霉素）的抗菌活性效力，以及（ 3) 评价纯化肽的热稳定性和细胞毒性。分子量为7.5 kDa的抗菌肽由SYFPGSTYGR 54-63位的10个氨基酸序列组成，被鉴定为tachystatin-A2。肽强烈抑制 2 种细菌菌株的生长，称为大肠杆菌ATCC 11775 和枯草芽孢杆菌ATCC 11774 的 MIC 值分别为 0.12 ± 0.09 和 0.12 ± 0.05 µg/mL。然而，对于金黄色葡萄球菌，这种抗菌肽的效力较低，仅在高浓度下才会发生活化（IC ₅₀值 = 15.63 ± 0.001 µg/mL）。在 30、50、70 和 100°C 下加热时，它是热稳定的。对人肝癌细胞 HepG2 系的细胞毒性测试显示 IC ₅₀值为 42.45 µg/mL，表明是一种无毒肽。基于其广谱活性、热稳定性和无毒等独特特性，tachystatin-A2 作为抗菌产品的候选者具有巨大的潜力。