農業部-水產試驗所全球資訊網農業部-水產試驗所全球資訊網

本研究以蝦類常見之病原菌–哈維氏弧菌 (Vibrio harveyi) 作為研究對象，首先分離純化其胞外產物之蛋白分解酵素，進而分析細胞外產物及其純化之蛋白分解酵素對南美白蝦 (Litopenaeus vannamei) 之凝血因子與血藍素之影響。研究分離純化一種蛋白分解酵素，其分子量約為22 kDa、等電點為4.15，在pH為6及60 C 時具最大活性，屬熱不穩定型，會受到 AEBSF、bestatin、EDTA 和 EDTA-2Na、1,10-phenanthroline、iodoacetic acid、pepstatin A、phosphoramidon、PMSF 及L-cysteine 等抑制，屬於兼具絲氨酸型及金屬型特性的蛋白質分解酵素。哈維氏弧菌細胞外產物和純化之蛋白分解酵素對白蝦 (5 ± 0.5 g) 的LD50 (48 hr) 分別為1.52 及0.52 μg protein / g shrimp，當白蝦注射細胞外產物及純化之蛋白分解酵素後，皆會造成白蝦血淋巴之凝血蛋白質量下降，但對血藍素的影響不明顯。

A common pathogen of shrimp, Vibrio harveyi, was used in the present study. Firstly, the protease of V. harveyi extracellular products was isolated and purified to then be used in the subsequent evaluation of their effects on clotting factors and hemocyanin in white shrimp, Litopenaeus vannamei. The isolated and purified protease, being unstable in hyperthermal condition, possessed a molecular weight of about 22 kDa, an isoelectric point of 4.15, and its maximum activity was at pH 6 and 60°C. It is able to be inhibited by AEBSF, bestatin, EDTA, EDTA-2Na, 1,10-phenanthroline, iodoacetic acid, pepstatin A, phosphoramidon, PMSF, and L-cysteine, revealing characteristics of serine and metal forms. The 48 hours LD50 of V. harveyi extracellular products and purified protease injected into L. vannamei (5 ± 0.5 g) are 1.52 and 0.52 μg protein/g shrimp. The decreased coagulogen levels in haemolymph were observed in shrimps injected with of V. harveyi extracellular products and its purified protease; however, the effect on haemocyanin was insignificant.