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 。
Hereby, it may probably concern this band as a partial segment of pectinesterase of betula platyphalla
據此，可初步確定此片段是白
樺果膠
酶基因的部分片段。
At last, ctab - dna and sds - dna methods are used in this experiment. on the basis of optimizing experiment procedure and pcr system of the materials, the initial reversion transcription system and orthologus gene cloning technique are established
對這3種方法比較后，確定本實驗採用ctab - dna
酶消化法和sds - dna
酶消化法提取白
樺雄花芽組織的總rna 。
Since there are more things in the bud tissue of the male flower, such as phenolic compounds, polysacchrides, proteins and some other secondary metabolites, three methods used to isolate rna are tested in this assay, which are the enzyme digesting methods of ctab, ctab - dna and sds - dna
克服了常規方法和試劑盒無法提取出富含酚類化合物、多糖和一些尚無法確定的次級代謝產物的白樺花芽組織rna的障礙，提出了3種白樺雄花芽組織rna的提取方法： ctab 、 ctab - dna酶消化法和sds - dna酶消化法。
