Browsing by Author "Sudhanshu Kashyap"

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Homology modeling deduced tridimensional structure of Bacillus thuringiensis Cry1Ab18 toxin
(Termedia Publishing House Ltd., 2012) Sudhanshu Kashyap; Brahma Dev Singh; Devindra Vijay Amla
Cry1Ab18 is an δ-endotoxin produced by Bacillus thuringiensis strain. Till date the detailed mechanism of this toxin action is unclear. Therefore, solution of the three-dimensional structure of all Cry1 family members would be desirable for a comprehensive understanding of the initial mechanisms that underlie the toxicity of this type of toxin. Here, we predict a theoretical structural model of the newly reported Cry1Ab18 δ-endotoxin, using a homology modeling technique with the structure of Cry1Aa toxin molecule (resolution 2.25Å). Cry1Ab18 resembles Cry1Aa toxin by sharing a common three-domain structure. Domain I is composed of nine α helixes and one small β strand, domain II is composed of nine β strands and two α helixes and domain III consists of two α helixes and eleven β strands. This model supports the existing hypotheses of receptor insertion and will further provide the initiation point for the domain swapping experiments aimed towards improving protein toxicity, and will help in the deeper understanding of the mechanism of action of common toxins.
Variation in methanotrophic bacterial population along an altitude gradient at two slopes in tropical dry deciduous forest
(2007) Deen Dayal Giri; Prabhu Nath Shukla; Sudhanshu Kashyap; Priti Singh; Ajai Kumar Kashyap; Kapil Deo Pandey
Soil samples were collected from Panchamarhi dry deciduous forest in Satpuda Biosphere Reserve, India to determine the effect of hill slopes and altitude on the population size of methanotrophic bacteria. Population size, in range of 4×105-3.6×107 g-1 dry soil, was negatively correlated with altitude and increased exponentially (r2 = 0.97, P<0.001) at steep slope (60°) while logarithmically (r2 = 0.97, P<0.001) at low slope (45°). Soil organic C, total N, and soil moisture increased while C/N ratio and temperature decreased down the hill slope. The results indicated that nutritional status of the soil across the slopes determines the methanotrophic bacterial population size. © 2007 Elsevier Ltd. All rights reserved.