乳糖诱导重组人内皮抑素在大肠杆菌中的表达

使用乳糖作为诱导剂,摇瓶培养大肠杆菌Origami(pET-hES)发酵生产重组人内皮抑素,优化了诱导温度、诱导时机、诱导时间及诱导剂浓度四因素.利用SDS-PAGE电泳检测并分析上述各因素的优化效果.结果表明,25℃,在菌株对数生长初期(培养6 h,D600=0.8)加入乳糖至终浓度为8 g/L,诱导14 h,可溶性目的蛋白表达量占其总表达量的82%;总目的蛋白表达量占全菌总蛋白的35%,优于以异丙基硫代半乳糖苷(IPTG)为诱导剂的诱导效果(25%).     

乳糖诱导胸腺融合肽Tα1-TP5在大肠杆菌中的表达

目的研究用乳糖替代异丙基-β-D-硫代吡喃半乳糖苷(IPTG)作为诱导剂诱导胸腺融合肽Tα1-TP5表达,并优化诱导表达条件。方法在摇瓶发酵条件下,以乳糖作为诱导剂,SDS-PAGE电泳和AlphaEase凝胶电泳图像分析系统研究培养基组成、诱导剂浓度、诱导时机、诱导时间、诱导温度和诱导方式等条件对目的肽Tα1-TP5表达量的影响,并与IPTG诱导结果相比较。结果选用TB培养基,在菌体对数生长的中后期加入终浓度为1 g/L的乳糖,37℃诱导6 h,GST-Tα1-TP5融合蛋白的表达量约占菌体总蛋白的35%,且主要以可溶形式表达,与IPTG的诱导结果相同。分批流加乳糖4次和一次性加入乳糖诱导,融合蛋白表达量无明显差异。结论乳糖可以替代IPTG诱导胸腺融合肽Tα1-TP5的表达。     

重组人Shiga-EGF工程菌发酵工艺研究

目的研究表达重组人Shiga EGF(rhShiga EGF)融合蛋白工程菌的发酵条件。方法通过摇瓶试验优选适合工程菌生长、表达的培养基配方、pH及以乳糖替代IPTG作诱导剂等 ,并在 5L发酵罐上进行试验。 结果采用A3配方的培养基 ,在pH 6 .8条件下 ,以乳糖诱导表达 5h ,5L罐发酵工程菌菌密度 (A60 0nm)达到 15 ,菌体湿重 2 7g/L ,目的蛋白表达量约占菌体总蛋白的 15 %～ 2 0 %。结论确立以乳糖为诱导剂的发酵条件能降低目的蛋白制备成本     

RGD-TRAIL工程菌发酵工艺的摸索研究

经过培养基筛选、培养温度和诱导条件的优化,确定了表达RGD-TRAIL(RGD-TNF related apoptosis inducing ligand)融合蛋白的基因工程菌RT发酵的最佳条件为:TB培养基分别作为RGD-TRAIL的发酵培养基,发酵生长温度控制在37℃,诱导温度控制在25℃,IPTG的最佳诱导浓度为0.8 mmol/L。诱导16 h后目的蛋白表达量到30%,可溶性目的蛋白表达量达15%。并在10 L发酵罐进行验证,确定了发酵工艺。     

rHAP在大肠杆菌中的诱导条件优化

目的研究用乳糖替代异丙基-β-D-硫代半乳糖苷(IPTG)作为诱导剂进行重组rHAP的表达。方法研究了rHAP基因工程大肠杆菌的生长、工程菌表达rHAP时IPTG诱导表达的起始工程菌浓度、诱导物IPTG和乳糖的用量及乳糖诱导时间与rHAP表达水平之间的关系。结果在摇瓶实验中,通过优化,选择在培养物的A560值达到3.0时进行诱导剂诱导可以使重组蛋白的表达实现最大化;使用乳糖进行诱导,在浓度0.5 g/L时可以使rHAP的表达量与1 mmol/L的IPTG诱导时相当;诱导时间控制在3 h可使目的蛋白的产生量达到最大,能够占到总可溶性蛋白的20%。结论获得了使用乳糖作为诱导剂获得rHAP的最适诱导条件,降低了成本,为规模化生产打下了基础。     

乳糖诱导重组人SOD基因在大肠杆菌中的表达

利用乳糖代替IPTG诱导rhCu/Zn-SOD在大肠杆菌(Escherichia coli）BL21（DE3）中的表达,并将菌体生长情况及产物表达规律与IPTG诱导进行比较。对诱导所需的乳糖浓度、金属离子浓度等因素进行了研究,并分析了低温下诱导对重组蛋白表达的影响。最终在摇瓶发酵条件的基础上,实现了乳糖诱导重组菌的5L全自动发酵罐培养,rhCu/Zn-SOD酶活性达到1810U/ml(发酵液）。结果表明,乳糖可以诱导rhCu/Zn-SOD在Escherichia coli中的表达,并且酶活性达到IPTG诱导时的89%。     

以乳糖为诱导剂的高密度发酵

以重组桐胰蛋白酶抑制剂（rETIa)为目的产物,用摇瓶比较了以异丙基－β-D－半乳糖苷和乳糖诱导表达的差异,并在15L发酵罐中,以乳糖为诱导剂进行高密度发酵,摸索了诱导后碳,氮补加工艺对产物表达的影响,成功地使菌体密度达到61（A600）,表达量达到菌体总蛋白的33％,为乳糖替代IPTG在工业生产中应用提供了借鉴。     

重组人肝增强因子工程菌JM109的发酵工艺研究

目的：研究表达重组人肝增强团子（hALR）工程菌JM109的发酵工艺。方法：采用发酵罐发酵,优化工程菌发酵的培养基配方、pH值、诱导表达时间、补料方式等。结果：在pH6．9条件下,培养6h后诱导表达5h,同时补科,5L罐发酵工程菌,菌体收得量可达湿重33．0g／L。目标蛋白表达量约占菌体总蛋白的31．3％。结论：此发酵工艺可以较好地提高ALR工程菌菌体得率和目标蛋白表达量。     

抗阿尔茨海默病神经保护肽[Gly14]-Humanin融合基因工程菌发酵工艺研究

目的优化大肠杆菌表达重组[Gly14]-Humanin(HNG)融合基因工程菌的发酵工艺。方法在15L发酵罐内,研究培养基、培养条件和诱导时间对工程菌生长和目的蛋白表达的影响,并考察工程菌中重组质粒的遗传稳定性。结果工程菌在pH7.4的2×YT培养基中诱导5h,菌体湿重可达80g/L,目的蛋白表达量约占总蛋白的36%,所构建的重组质粒在BL21宿主菌中传代稳定。结论优化了HNG融合基因工程菌的发酵和表达条件,为药物中试研究和规模化生产奠定了基础。     

重组人胰岛素样生长因子-Ⅰ工程菌高密度发酵工艺优化

目的优化表达重组人胰岛素样生长因子-Ⅰ(IGF-Ⅰ)工程菌的高密度发酵条件。方法考察培养基以及诱导时机、诱导剂量和诱导时间对蛋白表达的影响;用自控发酵罐进行分批补料培养实验,确定优化工艺条件。结果以2×YT+0.5%葡萄糖为发酵培养基,经0.8 mmol/L IPTG(异丙基-β-D-硫代半乳糖苷)诱导5 h,通过pH-stat反馈补料方式实现工程菌高密度发酵与目的蛋白高效表达,每1 L发酵液收获干菌体50.1 g,IGF-Ⅰ含量达5.25 g/L。结论建立了IGF-Ⅰ工程菌优化的高密度发酵工艺,为IGF-Ⅰ的下游纯化和工业化生产奠定了基础。     

乳糖诱导人胰岛素样生长因子-1在大肠杆菌中的表达

目的以含有人源性胰岛素样生长因子-1（hIGF-1）基因的大肠杆菌DH5a为研究对象,研究以乳糖作为诱导剂时目的融合蛋白的表达规律。方法利用可表达hIGF-1的工程菌,研究乳糖代替IPTG诱导大肠杆菌在不同条件下表达目的蛋白的一般规律．并优化表达条件,表达结果借助SDS-PAGE等方法进行分析。结果乳糖可诱导hIGF-1在大肠杆菌中的表达．最优表达条件为37℃下重组菌株生长至OD600值为0．7时加入诱导浓度为0．8％的乳糖继续诱导4h。诱导的目的融合蛋白相对表达量能够达到占总蛋白的40-60％水平,接近IPTG的诱导表达水平。结论乳糖能够代替IPTG作为诱导剂成功诱导hIGF-1在大肠杆菌中的表达。     

胸腺素α1-胸腺五肽在大肠杆菌中的表达及表达条件优化

目的探讨胸腺素α1-胸腺五肽(Tα1-TP5)在大肠杆菌中的表达及表达条件优化。方法将化学合成的Tα1-TP5基因与原核表达载体pGEX-4T-1融合并转化至E.coliBL21(DE3),异丙基-β-D-硫代半乳糖苷(IPTG)诱导表达。利用SDS-PAGE电泳和AlphaEase凝胶电泳图像分析系统研究培养基组成、诱导时机、诱导温度、诱导剂浓度及诱导时间等条件对融合蛋白表达量的影响。融合蛋白经GST琼脂糖珠亲和色谱纯化及重组肠激酶切割后,电喷雾质谱鉴定Tα1-TP5。结果选用TB培养基,在菌体对数生长中后期加入终浓度为0.05 mmol/L的IPTG,37℃诱导5 h,GST融合蛋白的表达量最高,占菌体总蛋白的35.8%,且主要以可溶形式表达。Tα1-TP5的分子质量与理论值相似。结论 Tα1-TP5成功在E.coli中表达,并确定了最佳表达条件。     

CYP3A induction by N-hydroxyformamide tumor necrosis factor-alpha converting enzyme/matrix metalloproteinase inhibitors use of a pregname X receptor activation assay and primary hepatocyte culture for assessing induction potential in humans.

A series of N-hydroxyformamide tumor necrosis factor-alpha converting enzyme (TACE)/matrix metalloprotease (MMP) inhibitors were evaluated for their potential to induce human cytochrome P450 3A (CYP3A). Two in vitro assays were used: 1) a cell-based reporter gene assay for activation of the pregnane X receptor (PXR), and 2) a primary "sandwich" culture of human hepatocytes. Approximately 50 TACE/MMP inhibitors were evaluated in the human PXR assay. A range of PXR activation was observed, 0 to 150% of the activation of the known human CYP3A inducer rifampicin. Three TACE/MMP inhibitors were evaluated in rat and human hepatocytes. Significantly higher PXR activation/CYP3A induction was observed in PXR/hepatocyte models, respectively, for (2R,3S) 3-(formyl-hydroxyamino)-2-(2-methyl-1-propyl)-4-methylpentanoic acid [(1S,2S)-2-methyl-1-(2-pyridylcarbamoyl)-1-butyl]amide (GW3333) compared with (2R,3S)-6,6,6-trifluoro-3-[formyl(hydroxy)amino]-2-isobutyl-N-[(1S,2R)-2-methoxy-1-[(1,3-thiazol-2-ylamino)carbonyl]propyl]hexanamide (GW6495) and (2R)-N-[(1S)-2,2-dimethyl-1-[(methylamino)carbonyl]-propyl]-2-[(1S)-1-[formyl(hydroxy)amino]ethyl]-5-phenylpentanamide (GI4023). The CYP3A induction level achieved with GW3333 at a concentration of approximately 10 microM in human hepatocytes was comparable to that achieved with rifampicin at a concentration of 10 microM. The extent of rodent CYP3A induction caused by GW3333 was confirmed in vivo after daily oral administration for 14 days to rats. In conclusion, GW3333 is a potential inducer of CYP3A expression in vivo in humans, but other N-hydroxyformamides are less likely to induce CYP3A.     

Induction of hepatic cytochrome P-450 and drug metabolism by metyrapone in the rat: relevance to its effects in rat-liver cell culture

The ability of metyrapone to induce hepatic cytochrome P-450 and xenobiotic metabolism in rats and rat hepatocyte culture has been studied. Metyrapone is a phenobarbitone-type inducer in rats. When rat hepatocytes were cultured with beta-naphthoflavone, a polycyclic hydrocarbon-type induction pattern was observed. In contrast, the observed induction pattern of both phenobarbitone and metyrapone in cell culture differed from that obtained with these compounds in vivo. The relationship between the nature of the induction of hepatic xenobiotic metabolism by metyrapone in vivo and its effects in liver-cell culture are discussed.     

Effect of dexamethasone on cytochrome P-450 mediated metabolism of 2-acetylaminofluorene in cultured rat hepatocytes

The metabolism of 2-acetylaminofluorene (AAF) to its six oxidative metabolites has been used to investigate the effect of dexamethasone on cytochrome P-450 activity in cultured rat hepatocytes. In control hepatocytes the metabolism of AAF to its 1-, 5-, 7-, 9- and N-hydroxylated metabolites rapidly declined in culture over the first 24 hr while 3-hydroxylation remained relatively constant. These activities either remained unchanged or increased slightly during the next 48 hr in culture. The addition of dexamethasone (100 nM) to the culture medium had little effect in arresting the initial decline but by 72 hr the 7-, 5- and 3-hydroxylations increased to values 2.5, 16 and 21 times the respective 24-hr values. The inductive effect of dexamethasone on the 3- and 5-hydroxylations of AAF was maximal at 100 nM whereas the 7-hydroxylation increased linearly as a function of the dexamethasone concentration up to 1 microM. Cortisol and corticosterone and the non-glucocorticoids fluoxymesterone and methyltestosterone induced a pattern of AAF metabolism resembling that in dexamethasone-treated cultures, suggesting that a range of steroids not restricted to glucocorticoids may induce multiple cytochrome P-450 isozymes via related mechanisms. Pregnenolone 16 alpha-carbonitrile induced only the 7-hydroxylation of AAF probably reflecting induction of cytochrome P-450p. While dexamethasone was a strong inducer of the 3- and 5-hydroxylations of AAF in hepatocyte culture, assay of these activities in freshly isolated cells after in vivo treatment with dexamethasone showed a strong induction of 7-hydroxylation but only small effects on 3- and 5-hydroxylations. Indeed the profile of AAF metabolism induced in culture by dexamethasone resembles more closely the profile induced by 3-methylcholanthrene in vivo. These data suggest that factors yet to be identified strongly influence the steroid-induced pattern of cytochrome P-450 gene expression.     

Strain differences in hepatic cytochrome P450 1A and 3A expression between Sprague-Dawley and Wistar rats

Expression of hepatic cytochrome P450 (CYP) isoforms was compared in Sprague-Dawley (SD) and Wistar (WI) rats, which are commonly used strains in preclinical studies. Basal CYP1A1, CYP1A2, and CYP3A2 mRNA levels were higher in WI rats than in SD rats (by 8-, 3- and 2-fold, respectively). Treatment with phenobarbital, a potent CYP inducer, increased the predominance of expression of these three mRNAs in WI rats (by 26-, 4-, and 2-fold, respectively) along with the predominance of increased microsomal total P450 contents and smooth-surface endoplasmic reticulum in the centrilobular hepatocytes. CYP1A enzymatic activity was also higher in WI rats than in SD rats. No strain differences were observed in phenobarbital induction of CYP2B1/2, CYP2C6, or CYP3A1. CYP3A2 mRNA was more strongly induced by dexamethasone, a typical inducer of CYP3A, together with CYP3A1 mRNA, in WI rats than in SD rats (by 2-fold), whereas the CYP1A1 and CYP1A2 mRNA expression induced by beta-naphtoflavone, a typical inducer of CYP1A, did not differ between the two strains. Furthermore, WI rats exhibited predominantly arylhydrocarbon receptor, pregnane X receptor, and constitutive androstane receptor mRNAs, responsible for CYP1A or CYP3A induction, with phenobarbital or dexamethasone induction. In conclusion, significant, predominant expression of hepatic CYP1A and CYP3A mRNAs in WI rats was observed, possibly related to nuclear receptor-mediated induction. Considering the pharmacokinetic and toxicological importance of CYP1A and CYP3A, different outcomes might arise depending on the rat strains used in preclinical studies of drugs metabolized typically or mainly by both isoforms.