Ali F S, Abdel-Moneim A A
Department of Agricultural Microbiology, Faculty of Agriculture, Minia University, Egypt.
Zentralbl Mikrobiol. 1989;144(8):615-21. doi: 10.1016/s0232-4393(89)80122-2.
The best temperature for the preservation of A. flavus var. columnaris alpha-amylase was -5 degrees C followed by 5 degrees C. CaCl2 at 0.005 M had no effect on the activity in both temperatures. Repeated freezing (-5 degrees C) and thawing followed by freezing (-5 degrees C) had no effect on stability of alpha-amylase. On the other hand, 25 degrees C was the lowest preservation temperature without any effect on the stability on alpha-amylase. 0.005 M CaCl2 decreased the activity of alpha-amylase and reached a 100% inhibition at 35th day. The fungal alpha-amylase had an optimum temperature of 55 degrees C at pH 4.6, but had 60 degrees C in buffer containing 0.005 M CaCl2 and 50 degrees C in buffer containing 0.005 M Na2-EDTA. The addition of 0.01 M CaCl2 greatly increased the thermostability of alpha-amylase at 40, 45, 50, 55 and 60 degrees C for 30 min. Optimum pH for alpha-amylase only was 5, but in the presence of 0.01 M CaCl2 or Na2-EDTA 5.6. The enzyme only was stable for 4 h at 25 degrees C. Whereas addition of 0.01 M CaCl2 showed a loss of 4% compared to a 22% loss in the presence of 0.01 M Na2-EDTA after 4 h at 25 degrees C and 65% loss in the presence of 0.01 M CaCl2 together with 0.01 M Na2-EDTA in the beginning and a 100% loss after 4 h at 25 degrees C. The optimum temperature for the activity of alpha-amylase at pH 5 was 50 degrees C for the enzyme only but 55 degrees C in the presence of 0.01 M CaCl2. However, at pH 6 and 7 optimum temperature was 55 degrees C for the activity of the enzyme only or with 0.01 M CaCl2. The presence of 0.01 M CaCl2 at pH 5, 6 and 7 resulted in increase of enzyme activity at the temperatures above 50, 40 and 25 degrees C, respectively. However, 0.01 M CaCl2 at pH 5 and 6 resulted in decreasing enzyme activity at temperatures below 55 and 45 degrees C, respectively.
黄曲霉柱晶变种α-淀粉酶的最佳保存温度是-5℃，其次是5℃。0.005M的氯化钙在这两个温度下对其活性均无影响。反复冷冻（-5℃）和解冻后再冷冻（-5℃）对α-淀粉酶的稳定性没有影响。另一方面，25℃是最低的保存温度，对α-淀粉酶的稳定性没有任何影响。0.005M氯化钙会降低α-淀粉酶的活性，在第35天达到100%抑制。该真菌α-淀粉酶在pH 4.6时的最适温度为55℃，但在含有0.005M氯化钙的缓冲液中为60℃，在含有0.005M Na2-EDTA的缓冲液中为50℃。添加0.01M氯化钙可大大提高α-淀粉酶在40、45、50、55和60℃下30分钟的热稳定性。仅α-淀粉酶的最适pH为5，但在存在0.01M氯化钙或Na2-EDTA时为5.6。该酶在25℃下仅稳定4小时。而添加0.01M氯化钙在25℃下4小时后活性损失4%，相比之下，在存在0.01M Na2-EDTA时损失22%，在同时存在0.01M氯化钙和0.01M Na2-EDTA时开始时活性损失65%，在25℃下4小时后损失100%。仅α-淀粉酶在pH 5时活性的最适温度为50℃，但在存在0.01M氯化钙时为55℃。然而，在pH 6和7时，仅酶或与0.01M氯化钙一起时活性的最适温度为55℃。在pH 5、6和7时存在0.01M氯化钙分别导致在高于50、40和25℃的温度下酶活性增加。然而，在pH 5和6时，0.01M氯化钙分别导致在低于55和45℃的温度下酶活性降低。
