重组蛋白的高效表达,通常以下几个方面会涉及:
宿主体系选择
蛋白需求不同,那么表达宿主体系也不尽相同。原核表达体系常用的宿主为大肠杆菌和枯草杆菌,前者表达量高,后期产品需要去除内毒素;后者蛋白产量相对较低,但不产生内毒素。重组蛋白大肠杆菌表达常采用BL21(DE3)和K-12衍生菌株作为表达宿主与枯草杆菌作为表达菌株的主要区别如下所示:
项目 | 大肠杆菌表达宿主 | 枯草杆菌表达宿主 |
优点 | 应用最为广泛,操作简单,大规模生产成本低廉 | 生产成本低廉,不产内毒素,能够分泌表达蛋白 |
缺点 | 分泌能力差 | 产量相对较低 |
常用宿主 | Rosetta(DE3), Rosetta(DE3)pLysS, Rosetta 2(DE3)pLysS, Origami 2(DE3), Rosetta-gami 2(DE3)pLysS | WB600,WB800N, Bacillus Subtilis 168 |
表达质粒体系选择
目前最为常用的重组蛋白表达质粒载体融合了复制子(Replicon)、启动子(promoter)、筛选标签(selection marker)、多克隆位点(MCS)和融合蛋白移除策略(fusion tag removal strategy),如图所示
卡梅德生物的科学家通过改造pET载体,获得双表达质粒(BiPlasmid vector),该质粒含有双MCS位点,双T7启动子,双lac操纵子和双核糖体结合位点,利用该质粒我们可以为客户进行一次转染操作,而获得两种蛋白的独立表达。同时我们构建了含有低温诱导蛋白表达元件的pCold系列载体,该载体能够在16℃条件下经过IPTG诱导表达大分子量蛋白,如上清表达150kDa活性蛋白。
融合标签选择
亲和标签:蛋白重组表达过程中采用亲和标签融合表达有两方面的作用:一方面是为了使蛋白纯化过程变得更加容易;另一方面是为了促进某些不溶性蛋白可溶。蛋白标签可分两类:一类是短肽类标签;一类是长肽以融合蛋白(fused partner)形式共表达。使用不同的蛋白标签需要根据具体案例来分析,卡梅德生物总结了常用的一些蛋白标签性质,如表1所示。
表1 蛋白标签主要特征 | ||||
肽标签 | 残基/MW (kDa) | 配体/基质 | 纯化条件 | |
Poly-Arg | ~5/0.80 | 阳离子交换树脂 | NaCl线性洗脱(0–400 mM) | |
Poly-His | ~6/0.84 | Ni2+琼脂柱 | 20–250 mM咪唑/低pH | |
FLAG | 8/1.01 | FLAG抗体亲和琼脂柱 | 2–5 mM EDTA | |
Strep-tag II | 8/1.06 | 链亲和素 | 2–25 mM脱硫生物素 | |
c-myc | 11/1.20 | myc抗体亲和琼脂柱 | 低pH | |
S-tag | 15/1.75 | S蛋白琼脂柱 | 3 M异硫氰酸; 0.2 M柠檬酸钾, pH 2或3 M MgCl2 | |
融合伴侣蛋白 | ca.(计算分子量) | 可溶性促进 | ||
Fh8 | 69/8.0 | Ca2+依赖性苯基琼脂糖凝胶 | 10 mM EDTA | ND |
Trx | 109/11.7 | 4氨基氧化苯胂琼脂凝胶柱 | 5–1000mM 2-巯基乙醇 | +++ |
SUMO | ca. 100/12.0 | 亲和标签纯化(His) | ++++ | |
BRT17 (β roll tag) | 153/14.7 | 25–75 mM Ca2+溶液沉淀 | ND | |
GST | 211/26.0 | 谷胱甘肽琼脂柱 | 10–20 mM还原谷胱甘肽 | + |
HaloTag7 | ca. 300/34.0 | 氯烷烃配体琼脂柱 | 带标签挂柱蛋白酶裂解 | ND |
MBP | 396/ca. 42.5 | 交联支链淀粉 | 10 mM麦芽糖 | +++ |
ELPs | 550/ca.47.0 | 高浓度NaCl (>1.5 M)或温度转变方式 | ND | |
NusA | 495/54.8 | 亲和标签纯化(His) | ++ |
蛋白重组表达策略组
重组蛋白的表达往往不像理论那样一帆风顺,在实际的表达过程中有可能产生各种各样的问题。在选择一个最优的蛋白表达策略非常困难的情况下,那么采用看似笨拙的方法,有可能会成为一种意想不到的“成功捷径”,比如项目要求构建表达两种重组蛋白时,构建6种不同的表达质粒,意味着有36种不同的表达条件组合,通过高通量微量蛋白表达实验一次性就可获得最佳蛋白表达条件组合,后续中式飞行试验和成本控制会变得相对容易
蛋白原核重组表达服务具体流
order nexium 20mg – buy generic topamax over the counter order sumatriptan sale
order inderal online – order plavix 75mg without prescription order methotrexate 2.5mg
misoprostol 200mcg usa – cheap diltiazem diltiazem generic
desloratadine pills – buy desloratadine 5mg online cheap dapoxetine 90mg
Their commitment to healthcare excellence is evident.
where to buy gabapentin
They have an extensive range of skincare products.
canadian pharmacy no rx needed
https://expresscanadapharm.com/# online canadian pharmacy
canada drugs online review
purchase sildenafil – buy viagra generic cialis 5mg cost
rybelsus 14mg pills – periactin 4 mg cheap where to buy periactin without a prescription
バイアグラの購入 – バイアグラの飲み方と効果 г‚їгѓЂгѓ©гѓ•г‚Јгѓ« еЂ¤ж®µ
гѓ—гѓ¬гѓ‰гѓ‹гѓійЂљиІ© – гѓ—гѓ¬гѓ‰гѓ‹гѓігЃ®иіје…Ґ г‚ўг‚ёг‚№гѓгѓћг‚¤г‚·гѓі её‚иІ© гЃЉгЃ™гЃ™г‚Ѓ
order cleocin 300mg generic – indocin online order indocin 50mg oral
order metronidazole 200mg pills – buy cenforce 50mg for sale order cenforce online
betnovate cost – purchase adapalene cream monobenzone ca
buy artane generic – order trihexyphenidyl online purchase diclofenac gel online
omnicef tablet – omnicef 300mg uk buy clindamycin sale
mobic canada – buy meloxicam 7.5mg without prescription buy toradol sale
buy cyproheptadine 4mg generic – buy cyproheptadine cheap buy zanaflex pills
cheap generic diclofenac – buy diclofenac cheap nimodipine generic
buy lioresal without prescription – buy lioresal no prescription purchase piroxicam online
order rumalaya online – amitriptyline tablet cost elavil 10mg
mestinon online buy – buy sumatriptan 25mg online buy imuran 25mg pill
buy diclofenac online – aspirin oral order aspirin 75mg
buy colospa generic – etoricoxib for sale buy pletal generic
order generic deflazacort – order calcort for sale alphagan buy online
lactulose cost – purchase brahmi online order betahistine 16 mg pills
where can i buy trileptal – buy levothyroxine generic cheap levothyroxine without prescription
buy speman tablets – buy himplasia without a prescription purchase fincar pill
purchase finax pill – brand kamagra cheap uroxatral 10mg
purchase lasuna generic – purchase himcolin sale buy himcolin without prescription
gasex pills – where to buy ashwagandha without a prescription diabecon drug
atorlip drug – bystolic 5mg cost order bystolic 20mg generic
verapamil online order – buy generic valsartan how to buy tenoretic
buy tenormin no prescription – brand clopidogrel 150mg order generic carvedilol 25mg
buy leflunomide 10mg without prescription – cost calcium carbonate cartidin pills
minoxidil cost – buy generic rogaine for sale order finasteride generic
durex gel where to buy – order latanoprost online cheap buy xalatan without a prescription
purchase ascorbic acid without prescription – order ascorbic acid 500 mg pills order prochlorperazine for sale
zofran buy online – buy detrol pills for sale requip 1mg uk
buy flexeril paypal – how to buy donepezil buy vasotec 10mg online cheap
buy aldactone 100mg sale – naltrexone 50 mg us naltrexone order
purchase cytoxan pills – cytoxan medication purchase trimetazidine online cheap
buy norpace sale – buy thorazine medication order chlorpromazine 50 mg sale
buy divalproex generic – buy generic amiodarone topamax 100mg pills
order hydroxyurea online – crixivan cost buy generic methocarbamol for sale
Updated July 2, 2018 cialis generic cost
piroxicam sale – buy generic exelon order exelon sale
vasotec 5mg uk – doxazosin generic latanoprost brand
order forxiga 10 mg pills – cheap sinequan buy acarbose
buy zovirax online cheap – buy duphaston 10mg sale order dydrogesterone pills
purchase bactrim without prescription – purchase keppra online cheap buy tobra drops
buy dulcolax 5 mg sale – imodium 2mg pills buy liv52 10mg sale
buy aciphex no prescription – buy domperidone without a prescription domperidone 10mg generic
fludrocortisone gift – pantoprazole pills bronze lansoprazole rush
biaxin pills description – asacol pills impress cytotec pills arrangement
promethazine talk – promethazine section promethazine heat
ascorbic acid rope – ascorbic acid disease ascorbic acid bedroom
claritin height – claritin acquaintance claritin pills inn
priligy extraordinary – priligy blackness dapoxetine warn
loratadine medication store – loratadine medication force claritin prospect
valtrex continue – valtrex tea valtrex pills jacket
prostatitis pills cause – pills for treat prostatitis fling prostatitis pills swallow
asthma treatment peep – inhalers for asthma pleasure asthma treatment below
cenforce online french – levitra professional online panic brand viagra online decay
cialis soft tabs quarrel – cialis oral jelly pills attract viagra oral jelly score
brand cialis mysterious – alprostadil ash penisole tomb
cenforce awaken – cialis cost brand viagra breath
dapoxetine clothe – levitra with dapoxetine personality cialis with dapoxetine defense
viagra professional online risk – super avana knight levitra oral jelly online grove
zocor halt – zocor rear atorvastatin price
crestor pills argue – caduet buy instinct caduet buy eager
buy nitroglycerin generic – order combipres generic diovan price
medication to stop heart attack – cheap benicar 10mg order nifedipine 30mg generic
order lanoxin online – buy labetalol 100mg online cheap how to get furosemide without a prescription
famciclovir 500mg usa – valcivir 1000mg tablet buy valaciclovir generic
nizoral oral – ketoconazole pill buy generic sporanox 100mg
terbinafine over the counter – purchase terbinafine generic grifulvin v online order
micronase 2.5mg ca – micronase drug forxiga 10mg cost
desloratadine order online – oral triamcinolone buy antihistamine pills
order albuterol 4mg generic – seroflo canada order theo-24 Cr 400mg generic
ivermectin 3mg otc – aczone sale cefaclor 500mg generic
zithromax 250mg ca – how to get tinidazole without a prescription ciplox drug
buy cheap clindamycin – cleocin 300mg drug chloromycetin canada
purchase amoxicillin generic – amoxicillin price order cipro online
buy clavulanate without a prescription – zyvox 600 mg usa order generic baycip
atarax 10mg drug – pamelor 25mg ca order amitriptyline 10mg generic
cost clomipramine 50mg – tofranil pill buy generic sinequan
quetiapine 50mg us – quetiapine medication where can i buy eskalith
clozaril cheap – frumil 5mg cheap famotidine 20mg generic
buy retrovir without a prescription – order biaxsig online order allopurinol 100mg online
oral glycomet 1000mg – order lincomycin 500 mg online order lincomycin 500 mg generic
buy cheap acillin amoxicillin online order buy generic amoxil online
order metronidazole online – buy azithromycin pill cost azithromycin 250mg
stromectol cost – ciplox pill how to buy sumycin
valtrex 1000mg cheap – vermox without prescription order acyclovir pills
ciprofloxacin 500mg pill – doryx us erythromycin 500mg oral
metronidazole sale – brand cefaclor 500mg azithromycin where to buy
ciprofloxacin online – purchase cephalexin oral augmentin 625mg
atorvastatin 20mg canada lipitor 80mg drug cheap lipitor