tailieunhanh - Báo cáo Y học: Short peptides are not reliable models of thermodynamic and kinetic properties of the N-terminal metal binding site in serum albumin

A comparative study of thermodynamic and kinetic aspects of Cu(II) and Ni(II) binding at the N-terminal binding site of human and bovine serum albumins (HSA and BSA, respectively) and short peptide analogues was performed using potentiometry and spectroscopic techniques. It was found that while qualitative aspects of interaction (spectra and structures of complexes, order of reactions) could be reproduced, the quantitative parameters (stability and rate constants) could not. | Eur. J. Biochem. 269 1323-1331 2002 FEBS 2002 Short peptides are not reliable models of thermodynamic and kinetic properties of the N-terminal metal binding site in serum albumin Magdalena Sokolowska 1 Artur Krezel1 Marcin Dyba1 Zbigniew Szewczuk1 and Wojciech Bal1 2 1Faculty of Chemistry University of Wroclaw Poland 2Institute of Biochemistry and Biophysics Polish Academy of Sciences Warsaw Poland A comparative study of thermodynamic and kinetic aspects of Cu II and Ni II binding at the N-terminal binding site of human and bovine serum albumins HSA and BSA respectively and short peptide analogues was performed using potentiometry and spectroscopic techniques. It was found that while qualitative aspects of interaction spectra and structures of complexes order of reactions could be reproduced the quantitative parameters stability and rate constants could not. The N-terminal site in HSA is much more similar to BSA than to short peptides reproducing the HSA sequence. A very strong influence of phosphate ions on the kinetics of Ni II interaction was found. This study demonstrates the limitations of short peptide modelling of Cu II and Ni II transport by albumins. Keywords serum albumin copper II nickel II binding constants rate constants. Human serum albumin HSA is the most abundant protein of blood serum at concentration of mM w 4 1 . It is a versatile carrier protein involved in the transport of hormones vitamins fatty acids xenobiotics drugs and metal ions including physiological Ca2 Zn2 Co2 and Cu2 as well as toxic Cd2 and Ni2 1-3 . This variety of functions is made possible by the presence of many binding sites on the surface of the HSA molecule including hydrophobic pockets of various sizes and shapes and coordination domains equipped with sets of donor groups appropriate for particular metals. Among the latter the N-terminal binding site for Cu2 and Ni2 ions has been characterized particularly well. It is composed of the first three amino-acid residues of .