• 作者： 賴慶亮
• 作者服務機構： 臺灣糖業研究所
• 中文摘要： 用螃蟹殼調製之幾丁質為擔體，研究其葡萄糖異構化酵素固定化條件，及其固定化酵素性質。在比較數種不同 glutaraldehyde 處理方法對幾丁質之酵素固定力影響之結果，未用 glu-taraldehyde 處理之幾丁質亦具有強力之酵素固定力。Glutaraldehyde 之處理未能提高其酵素固定力，但可增加固定化酵素之穩定性。酸、鹼處理為調製幾丁質作為擔體之必要手續，但其鹼處理濃度可由原來之 5N 減至 2N，而對葡萄糖異構化酵素之固定力不發生影響，幾丁質作為擔體最令人矚目之優點，為可直接用細胞抽取液，例如超音波處理液調製固定化酵素固定於幾丁質之葡萄糖異構化酵素，以矽膠在室溫乾燥，則活性顯著降低。因此固定化酵素之儲存以濕潤狀態保存於低溫處為宜。 以幾丁質固定化之葡萄糖異構化酵素之最適作用溫度及 pH，均與游離酵素者相同，未因固定化而有變化。固定化酵素之穩定性，對 pH 而言，以 6.0～7.5 為最佳，對溫度而言以60 C為最佳，在最適作用溫度75 C之穩定性，僅及60 C者之59％。固定化酵素與游離酵素之 Km甚接近，此表示酵素固定化後，未受基質擴散問題之影響。將固定於幾丁質及玻璃珠之葡萄糖異構化酵素以 Batch 方式，反覆使用比較其穩定性結果，在反覆使用六次後，前者尚保特原來活性之70％，而後者僅為10％。在Packed column之連續反應之初步試驗，該固定化酵素可維持高水準之異構化率達12天而後漸漸下降。
• 英文摘要： Chitin prepared from crab shell was usedas carrier for the immobilization of glucoseisomerase and the properties of the immobilizedglucose isomerase were investigated. Several me-thods of glutaraldehyde treatment were comparedwith their effect on the enzyme retaining abilityof chitin. The chitin without glutaraldehydetreatment retained the highest enzyme activity.Glutaraldehyde treatment did not increase theenzyme binding ability of chitin but increasedthe stability of the immobilized enzyme. Anacid-alkali pretreatment is an essential procedurefor the preparation of chitin, no remarkableinfluence on retention of the enzyme was ob-served when the concentration of alkali wasdecreased from 5N to 2N. Cell-free extractprepared by sonic treatment could be useddirectly as the enzyme source for the immobiliz-ation. The impurity presented in the cell-freeextract had little influence on the enzyme bindingability of the chitin. This striking propertymakes chitin as carrier for immobilization ofglucose isomerase more attractive. The immo-bilized enzyme lost the most of the activity ondrying over silica gel at room temperature. Thetemperature and pH optima for the immobilizedglucose isomerase were found similar to that ofthe native enzyme. Stability studies showedthat the best pH stability was in the range ofpH 6.0-7.5, and the best temperature stabilitywas around 60 C. The stability at the optimumtemperature of 75 C was only 59% of that of60 C. The Km values for the immobilized andthe native glucose isomerase were almost iden-tical, this indicates that diffusion does not exertany appreciable effect on the activity of theimmobilized enzyme. The operational stabilityof the immobilized enzyme was determined bybatchwise repeated use, and was compared withthat of the enzyme immobilized on glass beads.At the sixth run, the former retained about 70%of the initial activity and the latter diminishedto about 10%. The chitin-glucose isomerasesystem in column operation exhibited a highconversion rate for about 2 weeks of continuousisomerization of 40% glucose solution.
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