自龍膽石斑魚上皮黏液酵素水解物中篩選具抑制血管收縮素轉化酶活性之胜肽

高血壓是一種慢性病，亦是現在最普遍的文明病。雖然已有一些化學合成降血壓藥物被開發出來，但通常伴隨一些副作用。一般認為從天然物中得到的血管收縮素轉化酶抑制(ACEI)胜肽相較於化學合成的藥物就有較低的副作用。龍膽石斑 (Epinephelus lanceolatus)，為世界上最大的石斑魚種，屬暖水性魚類，分佈範圍廣泛，其生長快速及高單價讓牠迅速成為台灣海水養殖的優勢種。在魚皮表面遍佈粘液，其成分會因魚種差異而有所不同。許多文獻已有研究與報告，魚的表皮粘液的組成和特徵對於免疫能力非常重要，例如活性胜肽、抗菌蛋白、凝集素、溶菌酶及蛋白酶等。本研究為利用4種酵素 (pepsin、trypsin、chymotrypsin及thermolysin) 水解龍膽石斑上皮黏液16小時，並由其一水解物中篩選並製備具抑制ACE活性之短鏈胜肽。研究結果顯示，thermolysin水解物對ACE具有最佳抑制活性，其IC50為32.24±2.75μg/mL，並利用逆相高效能液相層析儀將此水解物進行成分分群，其中以第五分群具有最佳抑制ACE活性，並在此分液中篩選出LR-6及LE-5胜肽，合成後測定其抑制活性之IC50分別為737.5±84.72μM及29.92±4.5μM，其抑制劑型態分別為真實抑制劑型及藥物前驅物型。此研究成果可為龍膽石斑養殖業開發可能之生技產品，增加產業競爭力且提高產業產品的附加價值。

關鍵字

龍膽石斑；上皮黏液；血管收縮素轉化酶抑制劑；生物活性胜肽

並列摘要

Hypertension is a very common chronic disease nowadays. Although some chemically synthesized antihypertensive drugs have been developed, they are usually accompanied by side effects. Side effect of hypotensive active peptides is generally considered that are lower than that of synthetic one. Giant grouper (Epinephelus lanceolatus) is the largest grouper that belongs to warm-water species. It became a dominant species in Taiwan marine agriculture because of its fast growth rate and high price. Mucus composition varies throughout the epithelial surface and among fish species. The composition and characteristics of skin mucus is very important for the maintenance of its immune functions such as bioactive peptides, antibacterial proteins, lectins, lysozymes and proteases. The objectives of this study were to screen ACE inhibitory short-chain peptide from one of giant grouper epidermis mucus protein hydrolysate using different proteases (pepsin, trypsin, chymotrypsin and thermolysin) to hydrolysis for 16 hrs. The results indicated that thermolysin hydrolysate had the highest ACE inhibitory activity with the IC50 value of 32.24±2.75μg/mL. Fractionation of thermolytic hydrolysate was performed by reversed-phase high performance liquid chromatography (RP-HPLC). Fraction 5 showed the highest ACE inhibitory activity. LR-6 and LE-5 was chosen among all identified peptides from fraction 5, it has an IC50 value of 737.5±84.72μM and 29.92±4.5μM, the type of inhibitor is true inhibitor and prodrug, respectively. According to the results, development of biotech products of the peptide have improved the industrial competitiveness and economic value of the industrial products.