The stability constants of nickel (ii) complexes of amino acids with polar uncharged r – groups

Abstract

The dissociation constant,pKa of proline,threonine and asparagines were determined by potentiometric titration in aqueous solution.The pKa of proline,threonine and asparagines were found graphically by extrapolations to be 10.54, 10.31 and 9.39 respectively. The overall stability
constant of the corresponding nickel (II) complexes were also determined by potentiometric titration in aqueous solution. The values of the constant were found using ORIGIN 50 program to be 28.75, 2743 and 25.64 for nickel (II) prolinate, nickel (II) threoninate, and nickel (II)
asparaginate respectively. The number of coordinated amino acids to the nickel (II) ion in all the complexes was found to be three.