供货周期: | 现货 |
品牌: | LMAI Bio |
规格: | 100μl |
货号: | CAT#: LM1013 |
CAS号: |
Rosetta-gami 2(DE3)感受态细胞
Rosetta-gami 2(DE3) Chemically Competent Cell 产品说明书
产品规格 (CAT#: LM1013)
Rosetta-gami 2(DE3): 100μl/支
pUC19 (control vector,10pg/μl): 10μl
保存条件(保质期): -80℃(6个月)
Rosetta-gami 2(DE3)感受态细胞基因型
D(ara-leu)7697 DlacX74 DphoA PvuII phoR araD139 ahpC galE galK rpsL (DE3) F’[lac+ lacIq pro] gor522::Tn10 trxB pRARE2 (CamR, StrR, TetR)
Rosetta-gami 2(DE3)感受态细胞产品说明
Rosetta-gami 2(DE3) 菌株集合了Rosetta 2 和 Origami 2 两种菌株的优点:
* pRARE2赋予其Rosetta2菌株的优点——补充大肠杆菌缺乏的7种稀有密码子(AUA, AGG, AGA, CUA, CCC, GGA和CGG)对应的tRNA,提高外源基因的表达水平。
* gor522::Tn10 trxB赋予其Origami2菌株的优点——突变的硫氧还蛋白还原酶(thioredoxin reductase) (trxB)和谷胱甘肽还原酶(glutathione reductase) (gor)基因,它们是还原途径的两个关键酶,其突变有利于高效形成正确折叠的含有二硫键的蛋白,增强蛋白的可溶性;同时该菌株不具有卡那霉素抗性,可用于具有卡那霉素抗性质粒的蛋白表达。
* 该菌株染色体整合了λ噬菌体DE3区 (DE3区含有T7噬菌体RNA聚合酶)适合T7启动子诱导的蛋白表达。
* Rosetta-gami 2(DE3)菌株具有氯霉素,链霉素,四环素抗性,由特殊工艺制作,经pUC19质粒检测转化效率高达108cfu/μg DNA。
Rosetta-gami 2(DE3)感受态细胞操作方法
1. Rosetta-gami 2(DE3)菌株感受态细胞从-80℃拿出,迅速插入冰中,5分钟后待菌块融化,加入目的DNA并用手拨打EP管底轻轻混匀(避免用枪吸打),冰中静置25分钟。
2. 42℃水浴热激45秒,迅速放回冰上并静置2分钟,晃动会降低转化效率。
3. 向离心管中加入700 μl不含抗生素的无菌培养基 (2YT或LB),混匀后37℃,200 rpm复苏60分钟。
4. 5000 rpm离心一分钟收菌,留取100 μl左右上清轻轻吹打重悬菌块并涂布到含所选质粒筛选抗生素的2YT或LB培养基上。
5. 将平板倒置放于37℃培养箱过夜培养。
Sample Induction Protocol(for reference only)
1. Inoculate a single colony from a freshly streaked plate into 3ml of LB medium containing the appropriate antibiotic for the plasmid and host strain.
2. Incubate with shaking at 200 rpm at 37℃ overnight.
3. Inoculate 50 ml of LB medium containing the appropriate antibiotic with 0.5 ml of the overnight culture prepared in step 2(use the 500 ml triangular flask as the container would be better).
4. Incubate with shaking at 150 rpm at 37℃ until the OD 600 reaches 0.5-0.8. (0.6 recommended; about 2.5h).
5. (Optional)Pipet 1ml of the cultures into clean microcentrifuge tubes and place the tubes on ice until needed for gel analysis or storage at -20℃. These will serve as the non-induced control samples.
6. Add IPTG to a final concentration of 1 mM. Optimal time for induction of the target protein may vary from 2-16 hours, depending on the protein.
7. Incubate with shaking at 120 rpm at 37℃ for 2-4 hours. To determine the optimal time for induction of the target protein, it is recommended that a time course experiment be performed varying the induction from 2-16 hours.
8. Place the culture on ice for 10 minutes. Harvest cells by centrifugation at 5,000×g for 10 minutes at 4℃.
9. Remove the supernatant and store the cell pellet at -20℃ (storage at lower temperatures is also acceptable).
IPTG
Prepare a 1 M solution of IPTG (Isopropyl-β-D-thiogalactoside; Isopropyl-β-D-thiogalactopyranoside) by dissolving 2.38 g of IPTG in dd water and adjust the final volume to 10 ml. Filter sterilize before use.
注意事项
1. 感受态细胞最好在冰中缓慢融化,插入冰中8分钟内加入目标DNA,不可在冰中放置时间过长,长时间存放会降低转化效率。
2. 混入质粒时应轻柔操作。
3. 转化高浓度的质粒可相应减少最终用于涂板的菌量。
4. 诱导时,IPTG浓度可选(0.1-2 mM均可)。
5. 为获得需要量的蛋白,最佳诱导时间,温度,IPTG浓度需实验者优化。
同一批感受态细胞,用含目的片段的T载体质粒转化(阳性对照)能长出密密麻麻的菌落,而用另一种载体和目的片段的连接产物转化,却一个菌都没长出来,重复了三次都这样。请问这是感受态细胞的制作不过关,还是连接出了问题?哪个可能性大些?
答:应该是连接的问题。所有连接反应建议同时转化酶切后的质粒作为另一个阴性对照,确定酶切是否完全。同时连接前请确定质粒和片段浓度达到最小连接量的要求。
感受态细胞放到-80冰箱了有半年了,还能用来转化质粒吗?
答:如-80冰箱储存过程中没有发生冻融的情况,是可以用来转化的,但是由于冻存时间过长,转化效率会有所下降,如果用于普通的质粒重转或TA克隆等高效连接体系也是可以的,如珍贵的样品请选用较为新鲜的感受态细胞。
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