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51.
Ervatamia coronaria, a flowering plant (family Apocynaceae) indigenous to India, has medicinally important applications. A search for biochemical constituents of the latex of the plant yielded at least three thiol proteases with distinctly different properties. One of them, a highly active protease (ervatamin A), was purified to homogeneity by ion exchange and gel filtration chromatography. The enzyme exhibited high proteolytic activity toward natural substrates and amidolytic activity toward synthetic substrates. The pH and temperature optima for proteolytic activity were 8–8.5 and 50–55°C, respectively. Proteolytic activity of the enzyme was strongly inhibited by thiol-specific inhibitors. The estimated molecular mass of the enzyme was 27.6 kDa. The extinction coefficient (1% 280) of the enzyme was estimated as 21.9, and the protein molecule consists of 8 tryptophan, 11 tyrosine and 7 cysteine residues. Isoelectric point of the purified enzyme was 8.37. Polyclonal antibodies raised against the pure enzyme gave a single precipitin line in Ouchterlony's double immunodiffusion and a typical color in ELISA. The N-terminal sequence of the enzyme showed conserved amino acid residues to other plant cysteine proteases. Ervatamin A shows high activity in relation to the other thiol proteases isolated from the same source. 相似文献
52.
Menthol is a highly valued monoterpene produced by Japanese mint (Mentha arvensis) as a natural product with wide applications in cosmetics, confectionery, flavours, beverages and therapeutics. Selection
of high menthol yielding genotypes is therefore the ultimate objective of all genetic improvement programmes inMentha arvensis. A positive correlation was observed in the present study between menthol content in oils of evaluated genotypes and the
level of tolerance to externally supplied menthol of explants of these genotypes in culture medium. The easy use of this relationship
as a selectable biochemical marker opens the practical applicability of largescalein vitro screening of the germplasm, clones and breeders' material for selection of elite genotypes. 相似文献
53.
Ajit Kumar Shasany Suman P. S. Khanujia Sunita Dhawan Usha Yadav Srikant Sharma Sushil Kumar 《Journal of biosciences》1998,23(5):641-646
Media and incubation conditions have been defined for highly efficient regeneration of shoots from internode explants of slow
and fast growing cultivars ofMentha arvensis. Internodal segments excised from thein vitro raised shoots were inoculated on the MS medium supplemented with combinations of 5 concentrations of l-napthalene acetic
acid (NAA) and 3 concentrations of 6-benzyl amino purine (BAP). The media containing 2 μg ml−1 NAA, 10 Μg ml−1 BAP and 1 μg ml−1 NAA, 5 μg ml−1 BAP proved best for shoot regeneration and growth responses on cv Himalaya and cv Kalka explants, respectively. In 12 weeks
time, on average one explant of cv Himalaya produced about 200 shoots and that of cv Kalka produced about 180 shoots. The
Himalaya explants required higher concentrations of NAA and BAP for high efficiency proliferation as compared to the Kalka
explants. The experiments demonstrated that internodal tissue inMentha arvensis can be induced to obtain direct shoot regenerants with high efficiency. The analysis of the RAPD profiles of 100 regenerated
plantlets each of cv Himalaya and Kalka showed more than 99.9% homogeneity in bands with respect to the parents. 相似文献
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Aekyong Kim Suman Joseph Aslam Khan Charles J. Epstein Raymond Sobel Ting-Ting Huang 《Free radical biology & medicine》2010,48(11):1501-1512
Mn superoxide dismutase (MnSOD) is an important mitochondrial antioxidant enzyme, and elevated MnSOD levels have been shown to reduce tumor growth in part by suppressing cell proliferation. Studies with fibroblasts have shown that increased MnSOD expression prolongs cell cycle transition time in G1/S and favors entrance into the quiescent state. To determine if the same effect occurs during tissue regeneration in vivo, we used a transgenic mouse system with liver-specific MnSOD expression and a partial hepatectomy paradigm to induce synchronized in vivo cell proliferation during liver regeneration. We show in this experimental system that a 2.6-fold increase in MnSOD activity leads to delayed entry into S phase, as measured by reduction in bromodeoxyuridine (BrdU) incorporation and decreased expression of proliferative cell nuclear antigen (PCNA). Thus, compared to control mice with baseline MnSOD levels, transgenic mice with increased MnSOD expression in the liver have 23% fewer BrdU-positive cells and a marked attenuation of PCNA expression. The increase in MnSOD activity also leads to an increase in the mitochondrial form of thioredoxin (thioredoxin 2), but not in several other peroxidases examined, suggesting the importance of thioredoxin 2 in maintaining redox balance in mitochondria with elevated levels of MnSOD. 相似文献
58.
Suman Mazumdar Suraksha Sachdeva Virander S. Chauhan Syed Shams Yazdani 《Bioprocess and biosystems engineering》2010,33(6):719-730
The C-terminal, 19-kDa domain of Plasmodium falciparum merozoite surface protein-1 (PfMSP-119) is among the leading vaccine candidate for malaria due to its essential role in erythrocyte invasion by the parasite. We
designed a synthetic gene for optimal expression of recombinant PfMSP-119 in Escherichia coli and developed a scalable process to obtain high-quality PfMSP-119. The synthetic gene construct yielded a fourfold higher expression level of PfMSP-119 in comparison to the native gene construct. Optimization of cultivation conditions in the bioreactor indicated important
role of yeast extract and substrate feeding strategy for obtaining enhanced expression of soluble and correctly folded PfMSP-119. It was observed that the higher expression level of PfMSP-119 was essentially associated with the generation of higher level of incorrectly folded PfMSP-119. A simple purification procedure comprising metal affinity and ion exchange chromatography was developed to purify correctly
folded form of PfMSP-119 from cell lysate. Biochemical and biophysical characterization of purified PfMSP-119 suggested that it was highly pure, homogeneous, and correctly folded. 相似文献
59.
Suman Mukherjee Angus L. Dawe Rebecca Creamer 《Journal of microbiological methods》2010,81(2):160-165
Undifilum oxytropis (Phylum: Ascomycota; Family: Pleosporaceae) is a slow growing endophytic fungus that produces a toxic alkaloid, swainsonine. This endophyte resides in locoweeds, which are perennial flowering legumes. Consumption of this fungus by grazing animals induces a neurological disorder called locoism. The alkaloid swainsonine, an α-mannosidase inhibitor, is responsible for the field toxicity related to locoism. Little is known about the biosynthetic pathway of swainsonine in endophytic fungi. Genetic manipulation of endophytic fungi is important to better understand biochemical pathways involved in alkaloid synthesis, but no transformation system has been available for studying such enzymes in Undifilum. In this study we report the development of protoplast and transformation system for U. oxytropis. Fungal mycelia required for generating protoplasts were grown in liquid culture, then harvested and processed with various enzymes. Protoplasts were transformed with a fungal specific vector driving the expression of Enhanced Green Florescent Protein (EGFP). The quality of transformed protoplasts and transformation efficiency were monitored during the process. In all cases, resistance to antibiotic hygromycin B was maintained. Such manipulation will open avenues for future research to decipher fungal metabolic pathways. 相似文献
60.
It is thought that the pathological cascade in Alzheimer's disease is initiated by the formation of amyloid-β (Aβ) peptide complexes on cell membranes. However, there is considerable debate about the nature of these complexes and the type of solution-phase Aβ aggregates that may contribute to their formation. Also, it is yet to be shown that Aβ attaches strongly to living cell membranes, and that this can happen at low, physiologically relevant Aβ concentrations. Here, we simultaneously measure the aggregate size and fluorescence lifetime of fluorescently labeled Aβ1-40 on and above the membrane of cultured PC12 cells at near-physiological concentrations. We find that at 350 nM Aβ concentration, large (>>10 nm average hydrodynamic radius) assemblies of codiffusing, membrane-attached Aβ molecules appear on the cell membrane together with a near-monomeric species. When the extracellular concentration is 150 nM, the membrane contains only the smaller species, but with a similar degree of attachment. At both concentrations, the extracellular solution contains only small (∼2.3 nm average hydrodynamic radius) Aβ oligomers or monomers. We conclude that at near-physiological concentrations only the small oligomeric Aβ species are relevant, they are capable of attaching to the cell membrane, and they assemble in situ to form much larger complexes. 相似文献