環木聚糖 的英文怎麼說
中文拼音 [huánmùjùtáng]
環木聚糖
英文
cyclolignan-
The recombinants were constructed by transforming ppic9 a - xynb into p. pastoris gs115. the assay results revealed that the xylanase gene xynb was overexpressed and secreted effectually in p. pastoris. in 3l fermentor the expression level of xylanase xynba exceeded 1200iu / ml and the expressed xylanase had normal bioactivity. the molecule weight of xynba was determined as about 31kd which is higher than 23kd of original enzyme xynb from streptomyces olivaceoviridis a1. xynbb was gotten by deglycasylation of xynba, whose molecule weight returned to 23kd. we comparised the enzymatic properties of xynba expressed in p. pastoris, xynbb deglycasylated from xynba and xynb produced from streptomyces olivaceoviridis al : there was little difference among the three enzymes on optimal ph, the optimal ph of xynb and xynba were both 5. 2, the optimal ph of xynbb was 5. 0 ; the optimal temperature of xynb and xynba were both 60 c, while the optimal temperature of xynbb was 50 ? ; because of glycosylation the thermal stability of xynba was better than xynb and xynbb ; the specific activity of xynba and xynbb were 883. 88iu / mg and 832. 5hu / mg respectively, which were both lower than 2814. 45iu / mg of xynb ; the km values of xynb and xynba were similar to each other which were 21. 56 ( g / kg ) and 20. 87 ( g / kg ), while the km value of xynbb was 27. 10 ( g / kg ) ; the fmax of xynba and xynbb were 4568umol / mg. min and 5329umol / mg. min respectively which were lower than 27623 umol / mg. min of xynb ; additionally all of the three enzymes did not display cellulase activity. they all had well resistance to pepsion and trypsin, and were not sensitive to metal iron, surface active agent and chelating agent. the analysis of different xylans enzymatic hydrolysate revealed : by xynba, that the main constitutions of enzymatic hydrolysate of birch wood xylans were xylotriose and xyloquaiose, which account for 68. 43 % and 16. 50 % respectively, additionally there was 11. 79 % of xylobiose ; the main constitutions of enzymatic hydrolysate of corncobs xylans were xylobiose and xylotriose, which account for 81. 78 % and 11. 55 %. the result indicated that this xylanase was a kind of 1, 4 - b - d - xylanohydrolase and was fit to used in industrial procession of xylooligosacc harides
進一步對xynba進行了脫糖基化處理得到xynbb ，其分子量恢復到23kd ，證明xynba是糖基化蛋白。通過對畢赤酵母重組表達的木聚糖酶xynba 、脫糖基化的木聚糖酶xynbb以及橄欖綠鏈黴菌a1所產原酶xynb之間酶學性質的比較發現：三種酶的最適ph差異不大， xynb和xynba均為5 . 2 ， xynbb為5 . 0 ； xynb和xynba的最適溫度均為60 ， xynbb降為50 ：在耐熱性上， xynba由於糖基化作用熱穩定性明顯高於未糖基化的xynb和xynbb ； xynba和xynbb的比活性分別為883 . 88iu mg和832 . 51iu mg ，明顯低於原酶的比活2814 . 45iu mg ； xynb和xynba的km值相當，分別為21 . 56 （ g kg ）和20 . 87 （ g kg ） ，而xynbb的km值較大為27 . 10 （ g kg ） ； xynba和xynbb的vmax相差不大，分別為4568 mol mg ? min和5329 mol mg ? min ，明顯低於xynb的27623 mol mg ? min此外三種酶均無纖維素酶活性，對胃蛋白酶和胰蛋白酶有很好的抗性，且對作用環境中的各種離子、表面活性劑、螯合劑不敏感。通過對不同木聚糖的酶解產物的糖份分析發現：以樺木木聚糖為底物時，酶解產物主要為木三糖和木四糖，含量分別為68 . 43和16 . 50 ，另外還含有11 . 79的木二糖；以玉米芯木聚糖為底物時，酶解產物主要為木二糖和木三糖，含量分別為81 . 78和11 . 55 。
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