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Obembe O.O.,Covenant University | Obembe O.O.,Plant Transformation Group
African Journal of Biotechnology | Year: 2010

The development of plant biotechnologies has been very rapid in recent times, especially in the developed countries. The technologies have created a new branch of biotechnology known as molecular farming, where plants are engineered to produce pharmaceutical and technical proteins in large quantities. An evaluation of the status of plant biotechnology development in Africa revealed that majority of the countries that are involved in biotech activities are still at the level of tissue culture applications. This calls for urgent and sincere commitments on the part of the various stakeholders in Africa, especially the governments, to the development of biotechnology capacity. © 2010 Academic Journals. Source

Chugh M.,Malaria Research Group | Sundararaman V.,Malaria Research Group | Kumar S.,Plant Transformation Group | Reddy V.S.,Plant Transformation Group | And 3 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2013

Malaria parasites use hemoglobin (Hb) as a major nutrient source in the intraerythrocytic stage, during which heme is converted to hemozoin (Hz). The formation of Hz is essential for parasite survival, but to date, the underlying mechanisms of Hb degradation and Hz formation are poorly understood. We report the presence of a ∼200-kDa protein complex in the food vacuole that is required for Hb degradation and Hz formation. This complex contains several parasite proteins, including falcipain 2/2', plasmepsin II, plasmepsin IV, histo aspartic protease, and heme detoxification protein. The association of these proteins is evident from coimmunoprecipitation followed by mass spectrometry, coelution from a gel filtration column, cosedimentation on a glycerol gradient, and in vitro protein interaction analyses. To functionally characterize this complex, we developed an in vitro assay using two of the proteins present in the complex. Our results show that falcipain 2 and heme detoxification protein associate with each other to efficiently convert Hb to Hz. We also used this in vitro assay to elucidate the modes of action of chloroquine and artemisinin. Our results reveal that both chloroquine and artemisinin act during the heme polymerization step, and chloroquine also acts at the Hb degradation step. These results may have important implications in the development of previously undefined antimalarials. Source

Obembe O.O.,Covenant University | Popoola J.O.,Covenant University | Leelavathi S.,Plant Transformation Group | Reddy S.V.,Plant Transformation Group
Biotechnology Advances | Year: 2011

Plant molecular farming (PMF) is a new branch of plant biotechnology, where plants are engineered to produce recombinant pharmaceutical and industrial proteins in large quantities. As an emerging subdivision of the biopharmaceutical industry, PMF is still trying to gain comparable social acceptance as the already established production systems that produce these high valued proteins in microbial, yeast, or mammalian expression systems. This article reviews the various cost-effective technologies and strategies, which are being developed to improve yield and quality of the plant-derived pharmaceuticals, thereby making plant-based production system suitable alternatives to the existing systems. It also attempts to overview the different novel plant-derived pharmaceuticals and non-pharmaceutical protein products that are at various stages of clinical development or commercialization. It then discusses the biosafety and regulatory issues, which are crucial (if strictly adhered to) to eliminating potential health and environmental risks, which in turn is necessary to earning favorable public perception, thus ensuring the success of the industry. © 2010 Elsevier Inc. Source

Pantaleoni L.,University of Pavia | Longoni P.,University of Pavia | Longoni P.,University of Geneva | Ferroni L.,University of Ferrara | And 5 more authors.
Protoplasma | Year: 2014

The high cost of recombinant enzymes for the production of biofuel from ligno-cellulosic biomass is a crucial factor affecting the economic sustainability of the process. The use of plants as biofactories for the production of the suitable recombinant enzymes might be an alternative to microbial fermentation. In the case of enzyme accumulation in chloroplasts, it is fundamental to focus on the issue of full photosynthetic efficiency of transplastomic plants in the field where they might be exposed to abiotic stress such as high light intensity and high temperature. Xylanases (EC, a group of enzymes that hydrolyse linear polysaccharides of beta-1,4-xylan into xylose, find an application in the biofuel industry favouring biomass saccharification along with other cell-wall degrading enzymes. In the present study, we analysed how a high level of accumulation of a thermostable xylanase in tobacco chloroplasts does not impact on photosynthetic performance of transplastomic plants grown outdoors. The recombinant enzyme was found to be stable during plant development, ex planta and after long-term storage. © Springer-Verlag Wien 2013. Source

Sidhu K.,Virology Group | Kumar S.,Plant Transformation Group | Reddy V.S.,Plant Transformation Group | Kumar V.,Virology Group
Biochemistry | Year: 2014

Many proteins rely on disulfide bonds formed between pairs of cysteines for the stability of their folded state and to keep regulatory control over their functions. The hepatitis B virus-encoded HBx oncoprotein is known to perform an overwhelming array of functions in the cell and has been implicated in the development of hepatocellular carcinoma. However, its structure has not been elucidated. HBx carries nine conserved cysteine residues that have proven to be crucial for its various functions. However, the status of disulfide bonds between the cysteine residues reported in previous studies remains discrepant because of the use of refolded recombinant HBx that may contain non-native disulfides. Now we have determined the disulfide linkages in soluble and biologically active recombinant maltose binding protein-HBx fusion protein using matrix-assisted laser desorption ionization time-of-flight mass spectrometry. We report four disulfide linkages in HBx protein, viz., between Cys7 and Cys69, Cys61 and Cys115, Cys78 and Cys137, and Cys17 and Cys143, based on the differential mobility of corresponding disulfide-linked peptide ions under reducing and nonreducing conditions. Cys148 was observed to be free. Site-directed mutagenesis of Cys143 and Cys148 with serine and functional analyses of these mutants affirmed the importance of these residues in the ability of HBx to potentiate Cdk2/cyclin E kinase activity and transcriptionally activate promoter reporter gene activity. Thus, this study identifies native disulfide linkages in the structure of a biologically active viral oncoprotein. © 2014 American Chemical Society. Source

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