Empirical Equations for Activity and Osmotic Coefficients

A system of equations for fitting the experimental activity and osmotic coefficients of single and mixed electrolytes in aqueous solutions has been empirically developed in the present research. The results obtained through the equations developed here are comparable to the Pitzer equations in terms of accuracy and range of fitting. The equation for activity coefficient developed in the present research compared to the Pitzer activity coefficient equation has a form which is conveinient for computational purposes. The equation for activity coefficients is ln g = -╎ZmZx╎AD[I1/2/(1 + bI1/2)] + E I ln(I) + J1I + J2I3/2 where, b is fixed parameter having a value of 1.8; E, J1, and J2 are floating parameters. The corresponding equation for osmotic coefficients is obtained through the Gibbs-Duhem equation. The parameters have been evaluated by a nonlinear least squares computer program. This program weights all the data points equally. Parameters for both the coefficients are presented. In most of the cases data recommended by Robinson and Stokes is used. In the case of the 2-2 electrolytes one additional parameter is included to obtain acceptable results instead of two by Pitzer. Representing the 2-2 electrolytes in this manner ignores association constants, and thereby simplifying the treatment of these electrolytes at higher solution concentrations. Treatment of mixed electrolytes involves, in addition to pure electrolyte terms, parameters to account for the mixing effects is utilised. Only a few mixed electrolytes involving osmotic coefficients as experimental data has been treated here, and the results obtained are comparable to Pitzer\u27s

Monoallelic NTHL1 Loss-of-Function Variants and Risk of Polyposis and Colorectal Cancer

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Single-stranded DNA binding protein from human malarial parasite Plasmodium falciparum is encoded in the nucleus and targeted to the apicoplast

Apicoplast, an essential organelle of human malaria parasite Plasmodium falciparum contains a ∼35 kb circular genome and is a possible target for therapy. Proteins required for the replication and maintenance of the apicoplast DNA are not clearly known. Here we report the presence of single–stranded DNA binding protein (SSB) in P falciparum. PfSSB is targeted to the apicoplast and it binds to apicoplast DNA. A strong ssDNA binding activity specific to SSB was also detected in P. falciparum lysate. Both the recombinant and endogenous proteins form tetramers and the homology modelling shows the presence of an oligosaccharide/oligonucleotide-binding fold responsible for ssDNA binding. Additionally, we used SSB as a tool to track the mechanism of delayed death phenomena shown by apicoplast targeted drugs ciprofloxacin and tetracycline. We find that the transport of PfSSB is severely affected during the second life cycle following drug treatment. Moreover, the translation of PfSSB protein and not the transcription of PfSSB seem to be down-regulated specifically during second life cycle although there is no considerable change in protein expression profile between drug-treated and untreated parasites. These results suggest dual control of translocation and translation of apicoplast targeted proteins behind the delayed death phenomena