1. The strain M 5 al of Klebsiella pneumoniae grows excellently with starches. We were able to show that besides the pullulanase associated with the external membrane of the cells the bacterium produces an inducible, extracellular cyclodextrin glucanotransferase [1,4-alpha-D-glucan-4-alpha-(1,4-alpha-glucano)-transferase (cyclising) (EC 2.4.1.19)]. Potato starch and cyclohexaamylose or cycloheptaamylose were found to be the best "inducing" carbon sources for the synthesis of the enzyme. When the bacteria are grown batchwise, maltose is a poorly "inducing" carbon source; larger quantities of the enzyme are synthesized by continuous cultivation with maltose as growth limiting factor. 2. For the determination of the cyclodextrin glucanotransferase-activity an assay method wsa worked out. 3. The enzyme could be separated from the culture filtrate and purified to more than 90% in few steps. At a total yield of 61.2% related to the activity of the culture filtrate employed we received an enzyme solution with the specific activity of 26.6 units/mg protein. Some properties of the enzyme are described. 4. The products formed from amylopectin by the enzyme were analyzed. Somewhat more than half the amylopectin was found as cyclodextrins. 29.3% of the cyclodextrin fraction were cycloheptaamylose, 47.2% cyclohexaamylose and 10.7% exo-branched cyclohexaamylose. 12.8% of cyclohexaamylose were obtained from a cyclodextrin glucanotransferase-limit dextrin after debranching by pullulanase and exposing the product to the action of the glucanotransferase again. 5. The importance of the cyclodextrin glucanotransferase for the utilization of starches by this strain of Klebsiella pneumoniae is discussed. After a first characterization the enzyme is compared to the amylase of Bacillus macerans.

译文

:1。肺炎克雷伯菌的菌株M 5 al与淀粉一起生长良好。我们能够证明,除与细胞外膜相关的支链淀粉酶外,细菌还产生诱导型胞外环糊精葡聚糖转移酶[1,4-α-D-葡聚糖-4-α-(1,4-α-葡聚糖) -转移酶(环化)(EC 2.4.1.19)]。发现马铃薯淀粉和环己淀粉或环庚淀粉是合成该酶的最佳“诱导”碳源。当细菌分批生长时,麦芽糖是不良的“诱导”碳源。通过以麦芽糖为生长限制因子的连续培养来合成大量的酶。 2.为了测定环糊精的葡糖基转移酶活性,制定了一种测定方法。 3.可以从培养滤液中分离出酶,并通过几个步骤将其纯化至90%以上。与所使用的培养滤液的活性有关的总产率为61.2%,我们获得了比活性为26.6单位/ mg蛋白质的酶溶液。描述了酶的一些特性。 4.分析了由支链淀粉通过酶形成的产物。发现大约一半以上的支链淀粉是环糊精。 29.3%的环糊精级分是环庚直链淀粉,47.2%的环己直链淀粉和10.7%的外分支支化的环己直链淀粉。在通过支链淀粉酶脱支并且使产物再次暴露于葡聚糖转移酶的作用之后,从环糊精葡聚糖转移酶-极限糊精中获得12.8%的环己糖。 5.讨论了环糊精葡聚糖转移酶对于该肺炎克雷伯氏菌菌株利用淀粉的重要性。在首次鉴定后,将该酶与马氏芽孢杆菌的淀粉酶进行比较。

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