• Title/Summary/Keyword: bioprocessing

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Solid-phase refolding of immobilized enterokinase for fusion protein cleavage

  • Kim, Min-Young;Na, Sea-Jin;Suh, Chang-Woo;Kim, Chang-Ho;Lee, Na-Hyun;Lee, Eun-Kyu
    • 한국생물공학회:학술대회논문집
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    • 2003.10a
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    • pp.555-559
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    • 2003
  • EK를 고정화하기 위해 니켈 친화결합 방법과 공유 결합형 고정화 방법을 수행하였으며 니켈 친화결합이 공유 결합형 고정화보다 높은 고정화 수율과 activity를 나타냈다. 풀림과 재접힘을 이용한 효소의 활성 회복은 공유결합형 고정화가 니켈 친화결합보다 높은 결과를 나타내었다. 또한 기질의 분자량 크기에 따른 절단율의 차이가 없었으므로 레진 공극 내부로의 확산도 차이에 의한 절단반응의 차이는 없는 것으로 나타났고, 기질 종류에 따른 EK의 활성은 작은 기질이 큰 기질보다 높은 활성을 보였다.

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Mitochondrially Targeted Bcl-2 and Bcl-XL Chimeras Elicit Different Apoptotic Responses

  • Liu, Sen;Pereira, Natasha Ann;Teo, Joong Jiat;Miller, Peter;Shah, Priya;Song, Zhiwei
    • Molecules and Cells
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    • v.24 no.3
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    • pp.378-387
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    • 2007
  • The Bcl-2 family of proteins interacts at the mitochondria to regulate apoptosis. However, the anti-apoptotic Bcl-2 and $Bcl-X_L$ are not completely localized to the mitochondria. In an attempt to generate Bcl-2 and $Bcl-X_L$ chimeras that are constitutively localized to the mitochondria, we substituted their C-terminal transmembrane tail or both the C-terminal transmembrane tail and the adjacent loop with the equivalent regions from Bak or Bax mutant (BaxS184V) as these regions determine the mitochondrial localization of Bak and Bax. The effects of these substitutions on subcellular localization and their activities were assessed following expression in HeLa and CHO K1 cells. The substitution of the C-terminal tail or the C-terminal tail and the adjacent loop of Bcl-2 with the equivalent regions from Bak or the Bax mutant resulted in its association with the mitochondria. This change in subcellular localization of Bcl-2 chimeras triggered cells to undergo apoptotic-like cell death. The localization of this Bcl-2 chimera to the mitochondria may be associated with the disruption of mitochondrial membrane potential. Unlike Bcl-2, the loop structure adjacent to the C-terminal tail in $Bcl-X_L$ is crucial for its localization. To localize the $Bcl-X_L$ chimeras to the mitochondria, the loop structure next to the C-terminal tail in $Bcl-X_L$ protein must remain intact and cannot be substituted by the loop from Bax or Bak. The chimeric $Bcl-X_L$ with both its C-terminal tail and the loop structure replaced by the equivalent regions of Bak or Bax mutant localized throughout the entire cytosol. The $Bcl-X_L$ chimeras that are targeted to the mitochondria and the wild type $Bcl-X_L$ provided same protection against cell death under several death inducing conditions.

Identification of HUGT1 as a Potential BiP Activator and a Cellular Target for Improvement of Recombinant Protein Production Using a cDNA Screening System

  • Ku, Sebastian Chih Yuan;Lwa, Teng Rhui;Giam, Maybelline;Yap, Miranda Gek Sim;Chao, Sheng-Hao
    • Molecules and Cells
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    • v.27 no.5
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    • pp.577-582
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    • 2009
  • The development of a high-throughput functional genomic screening provides a novel and expeditious approach in identifying critical genes involved in specific biological processes. Here we describe a cell-based cDNA screening system to identify the transcription activators of BiP, an endoplasmic reticulum (ER) chaperone protein. BiP promoter contains the ER stress element which is commonly present in the genes involved in unfolded protein response (UPR) that regulates protein secretion in cells. Therefore, the positive regulators of BiP may also be utilized to improve the recombinant protein production through modulation of UPR. Four BiP activators, including human UDP-glucose:glycoprotein glucosyltransferase 1 (HUGT1), are identified by the cDNA screening. Overexpression of HUGT1 leads to a significant increase in the production of recombinant erythropoietin, interferon ${\gamma}$, and monoclonal antibody in HEK293 cells. Our results demonstrate that the cDNA screening for BiP activators may be effective to identify the novel BiP regulators and HUGT1 may serve as an ideal target gene for improving the recombinant protein production in mammalian cells.