甘蔗渣纤维素固定化木瓜蛋白酶及其应用研究

STUDY OF BAGASSE-CELLULOSE FIXED-PAPAIN AND ITS APPLICATION

匀浆状甘蔗渣纤维素用NaOH活化后,顺次经过高碘酸钠、尿素、甲醛处理,成为高反应性固定化酶载体,可用于木瓜蛋白酶的固定化。其酶蛋白的结合量与甲醛处理时间、酶固定时间,溶液酶浓度等有关。甲醛处理最适时间为14h,酶固定8h后,载体结合酶量趋向稳定,溶液酶最佳浓度范围为1～2.0mg/ml粗酶。固定化酶活力回收达34.5％,半衰期35天。固定化酶和溶液酶的K_m值(底物酪蛋白,w/v,％)分别为0.12％和0.26％;固定化酶和溶液酶的最适pH分别为pH8.0和pH8.5;二者的最适温度均为60～70℃。固定化酶和溶液酶一样有底物抑制现象;固定化酶在6mol/L脲中处理6h活力趋向稳定,其活力为原有活力的46.7％。用固定化酶处理啤酒,啤酒浊皮下降了2～9.25倍,蛋白质含量下降了78.8％,冷藏120天,处理啤酒无冷混浊现象发生,同时啤酒原有风味和其它理化指标保持不变。

Homogenized bagasse-cellulose activated by NaOH and treated in turn with sodium periodate, urea, formaldehyde, was used in the fixation of papain as a fast reactional carrier. The binding capacity of the enzyme protein was related to the duration of formaldehyde treatment and enzyme fixation as well as the concentration of solution enzyme. The optimum time for formaldehyde treatment was fourteen hours. After papain was fixed for eighteen hours, the papain-combining capacity of the carrier tended to remain stable. The range of optimum concentration of solution enzyme was 1 to 2. 5 mg/ml raw enzyme. The recovery rate for fixed papain activity reached 34. 5%. The half-life was 35 days. The Km values (casein as substance % w/v)and optimum pH values for fixed papain and solution papain were 0.12%and 8. 0, 0. 26% and 8. 5 respectively. The optimum temperature for both of them was 60-70 degree Celsivs. Fixed papain showed substrate inhibition as solution papain also did. The activity of fixed papain treated with 6 mol/L urea for six hours tended to be stable, and was 46. 7% of the orginal activity.The clarification of beer treated with fixed papain was raised by 2-9.25 times, and the content of protein in beer decreased by 78. 8%, the treated beer refrigerated for 120 days did not show turbidity, while the original flavour of the beer and other physical and chemical indices remained unchanged.