ANTIPROLIFERATIVE EFFECT ON BREAST CANCER (MCF7) OF Moringa oleifera SEED EXTRACTS

Background: Moringa oleifera belongs to plant family, Moringaceae and popularly called ―wonderful tree‖, for it is used traditionally to cure many diseases including cancer in Africa and Asia, however, there is limited knowledge on cytotoxic activity of Moringa oleifera seeds on MCF7 breast cancer cell. The present study evaluated antiproliferative effect on MCF7 of the seed. Materials and Methods: Seeds of Moringa oleifera were grinded to powder and its phytochemicals were extracted using water and 80% ethanol solvents, part of the ethanolic extract were sequentially partitioned to fractions with four solvents (hexane, dichloromethane, chloroform, and n-butanol). Antiproliferative effects on MCF7 of the samples were determined. Finally, potent samples that significantly inhibited MCF7 growth were tested on MCF 10A. Results: Crude water extract, hexane and dichloromethane fractions of the seeds inhibited the proliferation of MCF7 with the following IC50 values 280 μg/ml, 130 μg/ml and 26 μg/ml respectively, however, of the 3 samples, only hexane fraction had minimal cytotoxic effect on MCF 10A (IC50 > 400μg/ml). Conclusion: Moringa oleifera seed has antiproliferative effect on MCF7

Regulation studies of phaC(C1 and C2) genes in Pseudomonas sp. USM 4-55

Among the various biodegradable plastics available, polyhydroxyalkanoates (PHAs) attract a lot of attention because these polymers are produced by bacteria and have thermoplastic properties. They are biodegradable, biocompatible, moisture resistant, versatile, have long shelf life and are made from renewable source materials (Pouton et al., 1996)

Cloning and characterization of polyhydroxyalkanoate (PHA) genes from Pseudomonas sp. isolated from Antarctica

Pseudomonas strains accumulate mediumchain-length poly(R)-3-hydroxyalkanoate (PHA) as carbon and energy source under conditions of limiting nutrients in the presence of an excess of carbon source (Fidler et al., 1992)

Biosynthetic production of human growth hormone gene in methylotrophic yeast, Pichia pastoris

Human growth hormone (hGH) is secreted from the anterior pituitary gland and exerts a wide variety of functions such as, IGF-1 production, protein synthesis, glucose metabolism, lipolysis, lipogenesis, and cell proliferation/differentiation (Isaksson et al., 1985; Press, 1988; Thorner and Vance, 1988; Strobl and Thomas, 1994)

The Impact of Diluted Detergents on Escherichia coli K12 (JM109)

The purpose of this study is to investigate the effect of diluted detergents namely, Clorox, Dettol and Aganol against Escherichia coli K12 (JM109), at different concentrations. Frequent usage of diluted detergents and disinfectants without knowing their effectiveness in killing microbes can act as a medium for infections in susceptible hosts. Moreover, it is known that the regular application of diluted detergents and disinfectants may actually cause antibiotic resistance. The efficacy of diluted detergents is determined by the minimum inhibition concentration (MIC) and the minimum bactericidal concentration (MBC) using tube dilution assay. The susceptibility test is conducted using the disc diffusion technique. Dettol and Clorox exhibited effective bacteriostatic agents where the MIC is 0.75%. The lowest concentration of Dettol and Clorox required to kill E. coli K12 (JM109) or MBC is at the concentration of 3.0% and 5.0%, respectively. Aganol showed less effective bacteriostatic and bactericidal agents, where it required higher MIC of 1.25% and MBC of 10%. The susceptibility test indicated that the Clorox is the most effective antibacterial agent with the minimum inhibition zone of 7 mm at a concentration of 1.75%. Higher concentrations of Dettol and Aganol (of 10% and 20%, respectively) are needed to exhibit the antibacterial activity with the minimum inhibition zone of 7 mm

An approach towards the prediction of protein tertiary structures: molecular modeling perspectives

Impressive advances in genomic sequencing technologies are flooding us with the complete genetic blueprints of human, rat, mouse, chimpanzee and various microorganisms at an extremely rapid pace. As these DNA sequences continue to accumulate, the challenge to determine the function of each gene is paramount. These functions are determined by their unique three-dimensional (3D) structures as a result of protein folding. Protein folding can be defined as the process in which proteins spontaneously arrange their linear sequence of amino acids into native 3D structures that will allow them to function properly. Thus, elucidation of the 3D structure of a protein is vital in understanding its function. However, it is not known how the newly synthesized polypeptide chains fold into a protein with specific function. It was not until 1973 that Anfinsen [1] postulated that all the information needed for a protein to correctly fold into its native structure is encoded solely in its amino acid sequence and that the native state of the protein is the conformation with the lowest energy. Consequently, this important principle has brought immense interests among the scientists to investigate how proteins fold into their native structures and eventually determine the correct functional fold for the proteins. The two most mature and conventional experimental techniques to solve the structure of a protein are the X-ray crystallography and Nuclear Magnetic Resonance (NMR). John Kendrew and Max Perutz shared the Nobel Prize in 1962 for their pioneering achievement in solving the atomic level structure of the protein myoglobin and hemoglobin, respectively, using X-ray diffraction. Since then, many protein structures were solved and various roles of proteins in living cells were known. Despite the accuracy and the advances of these experimental techniques, such methods are very costly and it may take months to years for solving one structure. The current number of 3D protein structures is very small compared to the number of protein sequences, creating a huge gap between them. It has become more pressing with the growth of genome sequencing projects providing protein sequences for which structural information is not available. As this gap is expected to keep on growing with the ongoing genome projects, the experimental techniques certainly cannot be expected to keep pace with the rapid flow of the sequences. This has caused an urgent need to accurately predict the 3D structure of proteins from the linear chain of amino acid sequence using other methods especially computational work that relies heavily on theoretical studies. However, despite decades of active research and the impressive advances [2,3,4,5], computational protein structure prediction and protein folding remain one of the most important unsolved problems in structural biology today [6,7,8]

Etude cristallographique d oxydoréductases impliquées dans la réponse au stress oxydatif chez le peuplier en vue de la compréhension de leur mécanisme catalytique

La structure de trois oxydoréductases (la glutathion peroxydase (Gpx), la thiorédoxine (Trx) et la glutarédoxine (Grx)) de Populus trichocarpa . deltoides (le peuplier) a été caractérisée par diffraction des rayons X. Les Gpxs forment un groupe d enzymes qui régulent la concentration des espèces réactives de l'oxygène (ROS) dans les cellules, et qui les protègent des effets d un stress oxydant. Contrairement à leurs homologues d origine animale, les Gpxs végétales ne dépendent pas du glutathion (GSH) mais des Trx pour leur fonctionnement. Dans cette étude, j'ai résolu les structures des formes réduite et oxydée de la Gpx5 de peuplier et montré que des changements conformationnels drastiques sont nécessaires pour passer d une forme à l autre. Les Trxs régulent diverses protéines cibles par la réduction de leur pont disulfure. Mon objectif était de comprendre le mécanisme catalytique d une nouvelle isoforme, la PtTrxh4, dont la capacité à accepter des électrons de la Grx a été récemment démontrée. Cette PtTrxh4 contient trois cystéines, la première localisée dans une extension en position N-terminale (Cys4) et deux situées dans le site actif classique (WC1GPC2) de la Trx. Les résolutions des structures de l enzyme sauvage et du mutant C4S m ont permis de proposer un mécanisme catalytique en quatre étapes en accord avec les études enzymatiques. Les Grxs sont des protéines qui utilisent des électrons du GSH en particulier pour catalyser des réactions d'échange de thiol-disulfure. Ici, je présente la structure de la PtGrxS12 (en complexe avec le GSH), la première structure de la Grx végétale de sous-classe 1 ayant un site actif de motif atypique 28WCSYS32.Three oxidoreductases (glutathione peroxidase, GPX; thioredoxin, Trx and glutaredoxin, Grx) from Populus trichocarpa . deltoides (poplar tree) were characterized using X-ray crystallography approach. GPXs are a group of enzymes that regulate the levels of oxygen species in cells, and protect them against oxidative damage. In this study, I have determined the crystal structures of the reduced and oxidized form of poplar GPX5 (PtGPX5). Comparison of both redox structures indicates that a drastic conformational change is necessary to bring the two distant cysteine residues together to form an intramolecular disulfide bond. Trxs regulate various protein partners through the thiol-disulfide(s) reduction. The aim of this study is thus to precisely describe the catalytic mechanism of a new isoform of Trx, PtTrxh4, since it has been demonstrated recently to be reduced by Grx. PtTrxh4 contains three cysteines; one localized in an N-terminal extension (Cys4) and two in the usual Trx active site (WC1GPC2). Two crystal structures of PtTrxh4 solved in this study, wild-type and C61S mutant, allow us to propose a four-step disulfide cascade catalytic mechanism in accordance with enzymatic studies. Grxs are highly conserved redox-proteins that utilize electrons from GSH particularly to catalyze thiol-disulfide exchange reactions. Here, I present the structure of glutathionylated PtGrxS12, the first structure of plant Grx of subclass 1 with an atypical 28WCSYS32 active site. Protein structures solved here shed lights to our understanding of the redox mechanism in plant and to the enzyme-substrate interactions.NANCY1-Bib. numérique (543959902) / SudocSudocFranceF

Phylogeny and Characterization of Three nifH-Homologous Genes from Paenibacillus azotofixans

In this paper, we report the cloning and characterization of three Paenibacillus azotofixans DNA regions containing genes involved in nitrogen fixation. Sequencing analysis revealed the presence of nifB1H1D1K1 gene organization in the 4,607-bp SacI DNA fragment. This is the first report of linkage of a nifB open reading frame upstream of the structural nif genes. The second (nifB2H2) and third (nifH3) nif homologues are confined within the 6,350-bp HindIII and 2,840-bp EcoRI DNA fragments, respectively. Phylogenetic analysis demonstrated that NifH1 and NifH2 form a monophyletic group among cyanobacterial NifH proteins. NifH3, on the other hand, clusters among NifH proteins of the highly divergent methanogenic archaea