Crowding, molecular volume and plasticity: An assessment involving crystallography, NMR and simulations.

The discrepancy between the X-ray and NMR structures of Mycobacterium tuberculosis peptidyl-tRNA hydrolase in relation to the functionally important plasticity of the molecule led to molecular dynamics simulations. The X-ray and the NMR studies along with the simulations indicated an inverse correlation between crowding and molecular volume. A detailed comparison of proteins for which X-ray and the NMR structures appears to confirm this correlation. In consonance with the reported results of the investigations in cellular compartments and aqueous solution, the comparison indicates that the crowding results in compaction of the molecule as well as change in its shape, which could specifically involve regions of the molecule important in function. Crowding could thus influence the action of proteins through modulation of the functionally important plasticity of the molecule.

Adsorption studies on teak leaves (Tectona grandis): removal of lead ions from wastewater.

Teak leaves (Tectona grandis) abundantly available in India showed high sorption capacity for lead ions and were found efficient for the removal of lead ions from aqueous solutions. The extent of removal was found to be dependent on pH, temperature, concentration of metal ions and the dose of adsorbent. Thermodynamic parameters were calculated at different temperatures. The sorbent once used can be regenerated and recycled two - three times almost with the same capacity. However, regeneration by column operation gave better results than batch process.

The use of testa of groundnut shell (Arachis hypogea) for the adsorption of Ni(II) from the aqueous system.

This paper presents the use of testa of groundnut shell for the removal of nickel from dilute aqueous solutions at laboratory scale. The adsorption isotherm of Ni(II) on the testa of groundnut shell was carried out by the batch adsorption process. Various parameters such as initial concentration, pH and amount of the adsorbent doses were studied. The experimental adsorption data obtained followed both Langmuir as well as Freundlich isotherms. Maximum adsorption (85%) was observed at pH 6. The monolayer adsorption capacity was found to be 18.79 mg/g, which is greater than most of the low-cost adsorbents reported.