摘要 本研究由50多個土壤樣品中分離出15,000株放線菌，其中以Actinomycetes H12有最高之轉麩胺酸醯胺基酶酵素活性。Actinomycetes H12於最適化液態培養條件下，培養可得轉麩胺酸醯胺基酶產量2.7 U/ml，較原始培養(TSB)條件下之轉麩胺酸醯胺基酶產量提高1.4倍，較S. ladakanum CCRC 12422之轉麩胺酸醯胺基酶高1.8倍，而與日本生產轉麩胺酸醯胺基酶之菌株Streptoverticillium sp. S-8112 產量2.5 U/ml相似。 Actinomycetes H12 之轉麩胺酸醯胺基酶蛋白質特性分析:其最適作用溫度40℃，熱穩定性在50℃下加熱30分鐘仍保有50%活性，最適作用pH 6-8。此轉麩胺酸醯胺基酶活性會受到Cu2+、 Zn2+明顯之抑制，但一價離子、Fe3+與Ca2+則不影響其活性。 Actinomycetes H12發酵槽液態培養至40-48小時，此時其酵素分泌至胞外比率仍低，利用此特性將發酵液高速離心後，可直接回收帶有酵素之菌泥，不經純化下其收率為85%，經冷凍乾燥後其活性不變，但發現有Escherichia coli，因之再輔以Co 60-10kGy照射殺死病原菌及生產菌，然其活性下降至65%，即使照射時加入抗氧化劑(β-carotene, ascorbic acid)亦不能改善提高其殘留活性。 We isolated 15,000 Actinomycetes strains from over 50 soil samples, one isolated strain H12 have the highest TGase activity. The TGase activity (2.7U/ml) under the optimal conditions was about 1.4-fold than the TSB medium condition and 1.8-fold than the TGase from S. ladakanum CCRC 12422, but it is similar to the enzyme from Streptovertecillium sp. S-8112 (2.5 U/ml). The crude TGase from Actinomycetes H12 had the optimum pH and temperature being pH 6-8 and 40℃, respectively. The stable pH range was 5-9 and thermal stability of the crude TGase remained 50% activity after treatment at 50℃ for 30 min. The metal ions, Cu2+ and Zn2+, inhibited the activity of TGase. The addition of monovalence, Fe3+ and Ca2+ did not affect the activity of TGase. When Actinomycetes H12 was cultured on fermentor after 40-48 hr, the extracellular TGase still low. So we centrifuged the culture fluid in a single step and with high yields (85%), then the TGase activity didn’t decrease after freeze-dry. There were contaminants in products, therefore we treatment with Co 60-10 kGy killing germs and Actinomycetes H12, but the enzyme activity is decreased (65%). It didn’t improve to raise the activity, even thought added β-carotene and ascorbic acid.
