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1.
几种酶的功能简介   总被引:1,自引:0,他引:1  
李士彦 《生物学教学》2006,31(12):65-66
1.1淀粉酶 淀粉酶有两种,即α-淀粉酶和β-淀粉酶,α-淀粉酶是内切淀粉酶,其作用部位是直链或支链淀粉。可以把直链淀粉切成麦芽糖,也可以直接从商链淀粉切成葡萄糖。对于支链淀粉,α-淀粉酶可以把它水解为葡萄糖、麦芽糖和α-极限糊精(仍然由许多葡萄糖分子构成的物质)。而β-淀粉酶是外切酶,直接作用于直链或支链淀粉,从淀粉的末端每次切下一个麦芽糖单位。  相似文献   

2.
以菠萝蜜种仁淀粉为原料,采用β-淀粉酶(酶活为91500U/g)单酶法制备麦芽糖浆,在单因素实验的基础上,通过正交试验对工艺条件进行了优化,最佳工艺条件确定为:淀粉乳质量浓度20g/100mL、按质量分数加酶8%、pH5.5、(糖化)水解温度54℃、糖化时间8h。结果表明,在此条件下得到的产物淀粉转化率为41.6%,麦芽糖得率为47.5%。粗产品再经浓缩,得到的麦芽糖浆可溶性固形物含量(质量分数)为75%,色泽淡黄、体态均一透明、粘稠,具有麦芽糖香味,适合作为食品和食品辅料。  相似文献   

3.
以玉米淀粉为原料,研究了玉米多孔淀粉制备过程中各种因素对产物成孔效果的影响,探讨了酶解成孔的机理,并对制备工艺进行了初步优化.在糖化酶和耐高温α-淀粉酶混合成的复合酶作用下,玉米淀粉水解制备玉米多孔淀粉的最佳工艺为:加酶量为按照理论水解55%淀粉的30倍加入量,糖化酶与耐高温α-淀粉酶的配比7:1,反应体系pH值5.6,酶解温度60℃,淀粉浓度60%,反应时间20h.反应后玉米淀粉的吸油率由16.15%提高到了47.59%.  相似文献   

4.
啤酒的简易酿制实验河南省潢川师范学校(465150)马志成实验目的:通过实验加深对淀粉、麦芽糖、葡萄糖、蛋白质性质的认识和理解.了解啤酒的工业酿制生产过程和实验室简易酿制方法.实验原理:麦芽淀粉在麦芽淀粉酶、麦芽糖酶的作用下,水解生成麦芽糖、葡萄糖....  相似文献   

5.
采用小麦淀粉进行精制,三聚磷酯钠进行磷酸酯化生产无碳复写纸 CB 涂料淀粉间隔基。试验结果表明:当氢氧化钙用量在0.3-0.4%时,蛋白质含量达到0.3%以下;当上层淀粉取样在70-80%时,粒径在15-25μm 范围的达65%左右,大于40μm 粒径小于1%,;当三聚磷酸钠的加入量为4%,尿素2%时其留着率可达0.8%以上。  相似文献   

6.
淀粉与碘的颜色反应与还原糖含量的关系   总被引:1,自引:1,他引:1  
将糖的定性实验和定量实验相结合,我们测定了淀粉遇碘呈不同颜色反应阶段还原糖的含量,给出定性实验一个量化的结果。当底物淀粉浓度为2g/L,加入α-淀粉酶为0.5u/mL时,0—2.5min呈蓝色,2.5—5.5min呈紫色,5.5—13.5min呈红色,13.5min后呈无色。对应颜色变化点还原糖的分解比率分别为45%(蓝色→紫色),66%(紫色→红色),76%(红色→无色)。  相似文献   

7.
通过正交设计试验,优化了巴氏梭状芽孢杆菌产1,3-丙二醇(1,3-propnaediol,简称1,3-PD)的最适发酵条件:发酵培养基最佳配方为:2%酵母膏+3.4%K2HPO4+1%(NH4)2SO4+50%甘油+0.015%FeCl2 7H2O 0.2%(v/v)微量元素溶液;接种量5%,发酵温度30℃,发酵初始pH值7.0,恒温箱培养48小时,1,3-丙二醇产量达32.45g/L。  相似文献   

8.
非晶颗粒态玉米淀粉不同条件下酶降解活性研究   总被引:6,自引:0,他引:6  
采用光学显微镜分析测试方法。对非晶颗粒态玉米淀粉不同条件下酶降解活性进行了观察和研究,结果发现,α-中温淀粉酶生物活性对非晶颗粒态淀粉作用能力高,使用较少量的酶作用于非晶颗粒淀粉。在颗粒表面上可以观察到明显变化.非晶颗粒态淀粉颗粒由于存在爆裂口。所以酶对非晶淀粉作用均从爆裂口开始,逐渐由爆裂口开始均匀扩张,颗粒模糊,最后颗粒消失,不同时间、酶量、温度对酶降解作用均产生一定影响.其中温度可明显加快酶降解速度,酶量的增加同样对酶降解产生显著影响.时间的延长也可以使非晶颗粒态淀粉逐渐降解,但变化较慢.  相似文献   

9.
以花后七周的朋娜、纽贺尔脐橙品种的幼果作为实验材料,挑取胚珠进行离休培养,在MT培养基上分别附加麦芽汁(2ml/L),6-BA(5mg/L)和麦芽汁+6-BA(2ml/L,5mgL)诱导愈伤组织及胚状体,获得21.3%(20.7%-21.3%,对照15%)(朋娜)18.1%(6.2%-18.1%,对照12.1%)(纽贺尔)的胚状体,试验结果显示附加成份能促进胚状体生成。而且胚状体及愈伤组织,在附加NAA(0.5mg/L)+BA(2ml/L)的MT培养基上,能较好地诱导多丛芽。多丛芽可在固体培养基上扦插生根,用权壳、积极试管苗为砧木进行嫁接成活率可达84.4%-91.9%,是敦好的方法。同时在培养基中加入AgNO3(5mg/L),多次继代培养,能筛选出胚性愈伤组织。  相似文献   

10.
吃饭时细细咀嚼就会尝到一股甜津津的味道,这就是因为唾液中的淀粉酶将饭粒中的部分淀粉水解成糊精、麦芽糖和葡萄糖等分子的缘故。为增加学生对酶催化淀粉水解的感性认识可做如下实验。互取甲乙两方试管各加入5mll%的新配制的淀粉溶液,然后向两支试管中分别加入1ml新鲜唾液和1ml蒸馏水。振荡后用37%的水浴加热两支试管(夏季在室温下放置即可)。2每隔3~4分钟取出几滴试管中的溶液用碘水检验一次;甲试管中的溶液颜色变浅,而己试管溶液颜色不变,一直为蓝色,十分钟后甲试管中的溶液加碘水不变色,表明淀粉已水解完全,而乙试管中的…  相似文献   

11.
《海外英语》2007,(5):44-45
It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,  相似文献   

12.
一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/  相似文献   

13.
《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?  相似文献   

14.
《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.  相似文献   

15.
汉字倒说     
汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。  相似文献   

16.
王菲 《华章》2007,(12):273-273
Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.  相似文献   

17.
裴水妹 《华章》2007,(11):196
Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.  相似文献   

18.
19.
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…  相似文献   

20.
钱生钱!     
我们绝大部分人都同意一件事情——我们喜欢金钱。但是你对金钱的喜欢之情足够到让你创立一份事业么?.财富通常被人忽视,主要在于人们不能真正了  相似文献   

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