A new method for purification of functional recombinant GST-cyclophilin A protein from E. coli.

The expression of glutathione-S-transferase (GST) fusion protein is extensively utilized in the study of protein-protein interactions. In the commonly used purification method, the overexpressed GST fusion protein is bound to the glutathione (GSH)-coupled resins via affinity chromatography, and then eluted by an excessive quantity of reduced GSH. However, this technique has certain limitations, such as low product purity, retention of GSH in the sample, as well as relatively high cost. To overcome these limitations, in this study, elution buffer containing 2% formic acid was utilized rather than GSH to elute the GST-fusion protein, and thereafter the acidic samples were neutralized using collecting buffer. By using this method, highly purified GST-cyclophilin A (CypA) fusion protein was obtained, without affecting the structural and functional characteristics such as PPIase and chaperone activities. Moreover, the procedure is also cost-effective, due to the low cost of formic acid as compared with GSH.

Conductometric study of AlCl3 in anhydrous formic and acetic acids

The ionic dissociation constant and limiting molar conductance of A1C1[3] have been determined by conductometric measurements in both anhydrous formic and acetic acids. The conductometric data were analyzed according to Onsager Sheldovsky and Kraus-Bray methods at different concentrations ranging from 3.71 x 10[-3] to 1.7 x 10[-3] mol dm [-3] at different temperatures [namely 30, 35 and 40 degree]. The dissociation constants of AlCL[3] in anhydrous formic acid are larger than those obtained in anhydrous acetic acid. The dissociation constant in case of anhydrous formic acid increases with temperature but decreases in case of anhydrous acetic acid. This has been interpreted based on the dielectric constant of both formic and acetic acid solutions in non-aqueous media