Effect of denaturants on the speciation of amino acid complexes-computer augmented modelling studies: VI - Protonation equilibria of <img src='http://www.niscair.res.in/jinfo/small.gif' border=0>-glutamic acid and <img src='http://www.niscair.res.in/jinfo/small.gif' border=0>-ornithine in anionic micellar media

Abstract

The effect of sodium lauryl sulphate(SLS) on the protonation equilibria of <img src='http://www.niscair.res.in/jinfo/small.gif' border=0>-glutamic acid and <img src='http://www.niscair.res.in/jinfo/small.gif' border=0>-ornithine has been studied in varying concentrations (0.5-2.5% w/w) of SLS solution maintaining an ionic strength of 0.16 mol dm^-3 at 303 K. The protonation constants have been evaluated with the computer program MINIQUAD 75 from the primary alkalimetric titration data. The selection of the best fit chemical models is based on chemical validation and residual analysis. All the three protonation constants of <img src='http://www.niscair.res.in/jinfo/small.gif' border=0>-glutamic acid decrease with increase in the SLS content. The same trend is observed for <img src='http://www.niscair.res.in/jinfo/small.gif' border=0>-ornithine except for log <i>K</i>₃, which increased at higher concentrations of SLS. This trend is attributed to the changes associated with the dielectric constant of the medium and to micellar effects.