Testing the ability of non-methylamine osmolytes present in kidney cells to counteract the deleterious effects of urea on structure, stability and function of proteins.

Human kidney cells are under constant urea stress due to its urine concentrating mechanism. It is believed that the deleterious effect of urea is counteracted by methylamine osmolytes (glycine betaine and glycerophosphocholine) present in kidney cells. A question arises: Do the stabilizing osmolytes, non-methylamines (myo-inositol, sorbitol and taurine) present in the kidney cells also counteract the deleterious effects of urea? To answer this question, we have measured structure, thermodynamic stability (ΔG D (o)) and functional activity parameters (K m and k cat) of different model proteins in the presence of various concentrations of urea and each non-methylamine osmolyte alone and in combination.

Why is glycine not a part of the osmoticum in the urea-rich cells?

Kidney cells of animals including human and marine invertebrates contain high amount of the protein denaturant, urea. Methylamine osmolytes are generally believed to offset the harmful effects of urea on proteins in vitro and in vivo. In this study we have investigated the possibility of glycine to counteract the effects of urea on three proteins by measuring thermodynamic stability, ΔGD° and functional activity parameters (K(m) and k(cat)).

Quantitative analysis of rabeprazole sodium in commercial dosage forms by spectrophotometry.

The main aim of this work is to develop and validate two spectrophotometric methods for the quantitative analysis of rabeprazole sodium in commercial dosage forms. Method A is based on the reaction of drug with 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) in the presence of ammonium cerium(IV) nitrate in acetic acid medium at room temperature to form red-brown product which absorbs maximally at 470 nm. Method B utilizes the reaction of rabeprazole sodium with 1-chloro-2,4-dinitrobenzene (CDNB) in dimethyl sulfoxide (DMSO) at 45+/-1 degrees C to form yellow colored Meisenheimer complex.

Kinetic spectrophotometric analysis of pantoprazole in commercial dosage forms.

A kinetic spectrophotometric method has been developed which is based on the oxidation of pantoprazole with Fe(III) in sulfuric acid medium. Fe(III) subsequently reduces to Fe(II), which is coupled with potassium ferricyanide to form Prussian blue. The reaction is followed spectrophotometrically by measuring the increase in absorbance with time (1-8 min) at 725 nm.