Spectrophotometric studies on the effect of two porphyrin compounds on structure and binding of human serum albumin.

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Spectrophotometric studies on the effect of two porphyrin compounds on

structure and binding of human serum albumin.

Ali Reza Teimoortash ¹, Davood Ajloo ¹ Saeed Zakavi ¹, Mona Asadzadeh

1, Mina Evini ², Ali Akbar Saboury ², Ali Akbar Moosavi-Movahedi ²,

1-School of Chemistry, Damghan University of Basic Science, Damgahn.

2-Institute of Biochemistry and Biophysics, The University of Tehran, Tehran E-mail: [email protected],

[email protected] , [email protected]

Abstract

Effect of two porphyrin; meso-tetrakis(4-sulphotanophenyl)porphyrin (H2TPPS4) and meso-tetrakis(3-sulphonato-4-methoxyphenyl)porphyrin (H2TAPS4) on the structure of human serum albumin (HSA) were investigated by UV-Vis spectrophotometery, circular dichroism (CD) fluorescence spectrophotometery and GROMACS molecular dynamics (MD) in different temperature (17, 27 and 37^oC), different pH (6.5, 7.5 and 8.5) and different ionic strength (10 mM, 50 mM and 100 mM). The results show that increasing the pH and ionic strength decreases the binding.

Increasing the temperature do not show the regular trend. The spectrophotometric results (CD and fluorescence) indicate that, both ligands unfolded the protein (decreasing the secondary and tertiary structure). The effect of H2TAPS4 on the midpoint transition temperature (Tm ) of HSA was investigated by fluorescence in different pH. It is resulted that HSA is more unfolded and less stable in lower pH.

Key words: spectrophotometry, Circular dichroism, Fluorescence, porphyrin, ligand binding, molecular dynamics.

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