Potentiometric Studies on Transition Metal (II) Essential Amino Acid Complexes

H. N. Aliyu and J. Na’aliya

Department of Chemistry Bayero University, P. M. B. 3011, Kano, Nigeria

*Corresponding Author E-mail: hnuhu2000@yahoo.com

Accepted 18 June, 2012

Abstract

Potentiometric Studies on complexes formed by essential metal ions and amino acids have been carried out. The dissociation constants of the amino acids, the stepwise formation constants and the overall stability constants of the metal (II) amino acid complexes were determined. The dissociation constants of the amino acids determined are; alanine (10.29), arginine (12.02), asparagine (9.39), glycine (9.87), histidine (7.01), lysine (9.28), methionine (9.68), phenyalanine (9.61), proline (10.53), threonine (10.31), tryptophan (9.77), and valine (10.28). The average number of coordinated amino acids to metal iron determined are 1:2 and 1:3 metal-ligand ratios respectively. The Stepwise Stability Constants of the complexes were determined using ‘ORIGIN 50’ Program and the values were found to decrease in the order K₁ > K₂ > K₃ for all the complexes. The value of overall stability constant (β) of each complex obtained is relatively high, indicating good stability for the complexes.

Key words: Potentiometry, complexes, Amino acids, stability constant and dissociation constant.