A theoretical study of acriflavin-DNA binding

A theoretical study of binding behaviour of acriflavin, a well-known mutagen, with DNA base pairs such as AT, GC, TA and CG has been performed using CNDO/2 method to compute net atomic charges and dipoles located at various centres in acriflavine as well as base pairs. Acriflavine-DNA base pair interactions have been evaluated using second order perturbation method with multicentered multipole approximation. Only minimum energy configurations have been reported. Results have been discussed with a view to obtain a comparative behaviour of other similar dyes like proflavine and acridine orange.     

Stacking interactions between demethylated ellipticines and DNA base pairs--a quantum mechanical study

A study of the binding behaviour of ellipticine compounds, derivatives of pyrido (4-3b) carbazole, has been carried out to elucidate the relationship between the drug-activity and demethylation of ellipticine. An all valence electron method (CNDO/2) has been employed to compute molecular charge distribution corresponding to various atomic centres of ellipticines and DNA base pairs. Using these atomic charges and dipoles, intermolecular interaction energy has been calculated with the help of second order perturbation theory and multicentered-multipole expansion technique. A comparative analysis of the binding patterns for nor-5,11-dimethyl-ellipticine and nor-11-methyl-ellipticine has been presented vis-a-vis ellipticine. Attempt has been made to correlate interaction energy studies with demethylation of ellipticine and the possible binding patterns.     

Characterization of glucose uptake by Trichuris globulosa (Nematoda) in vitro

14C-glucose uptake by adult Trichuris globulosa is found to be a non-linear function of time and limiting substrate concentration. The uptake is a two component process, an initial rapid burst is followed by a lower steady state, implying a mediated process. The uptake is dependent on Na+ ions which cannot be replaced by K+, Li+ or choline. The uptake is also dependent on pH, being maximal at pH 7.4. 14C-glucose absorption is markedly inhibited by glucose, phlorizin, ouabain and to a smaller extent by a number of monosaccharides and other sugar-phosphates, nucleosides and metabolic inhibitors like p-nitrophenyl phosphate and iodoacetate. The inhibition constant for glucose, phlorizin and ouabain has been found to be 8 mM, 5 mM and 7 mM, respectively. A modified Dixon-plot shows that glucose is a completely competitive inhibitor for 14C-glucose uptake while the nature of competitive inhibition of phlorizin and ouabain are found to be partial.     

Minichromosome maintenance proteins in eukaryotic chromosome segregation

Minichromosome maintenance (Mcm) proteins are well-known for their functions in DNA replication. However, their roles in chromosome segregation are yet to be reviewed in detail. Following the discovery in 1984, a group of Mcm proteins, known as the ARS-nonspecific group consisting of Mcm13, Mcm16-19, and Mcm21-22, were characterized as bonafide kinetochore proteins and were shown to play significant roles in the kinetochore assembly and high-fidelity chromosome segregation. This review focuses on the structure, function, and evolution of this group of Mcm proteins. Our in silico analysis of the physical interactors of these proteins reveals that they share non-overlapping functions despite being copurified in biochemically stable complexes. We have discussed the contrasting results reported in the literature and experimental strategies to address them. Taken together, this review focuses on the structure-function of the ARS-nonspecific Mcm proteins and their evolutionary flexibility to maintain genome stability in various organisms.     

Antioxidant enzyme responses of plants to heavy metal stress

Heavy metal pollutions caused by natural processes or anthropological activities such as metal industries, mining, mineral fertilizers, pesticides and others pose serious environmental problems in present days. Evidently there is an urgent need of efficient remediation techniques that can tackle problems of such extent, especially in polluted soil and water resources. Phytoremediation is one such approach that devices effective and affordable ways of engaging suitable plants to cleanse the nature. Excessive accumulation of metal in plant tissues are known to cause oxidative stress. These, in turn differentially affect other plant processes that lead to loss of cellular homeostasis resulting in adverse affects on their growth and development apart from others. Plants have limited mechanisms of stress avoidance and require flexible means of adaptation to changing. A common feature to combat stress factors is synchronized function of antioxidant enzymes that helps alleviating cellular damage by limiting reactive oxygen species (ROS). Although, ROS are inevitable byproducts from essential aerobic metabolisms, these are needed under sub-lethal levels for normal plant growth. Understanding the interplay between oxidative stress in plants and role of antioxidant enzymes can result in developing plants that can overcome oxidative stress with the expression of antioxidant enzymes. These mechanisms have been proving to have immense potential for remediating these metals through the process of phytoremediation. The aim of this review is to assemble our current understandings of role of antioxidant enzymes of plants subjected to heavy metal stress.