Abstract:

Meso-tetra(4-hydroxyphenyl)porphyrin (THPP) interacting with lysozyme was investigated by the fluorescence spectroscopy under simulate
d physiological conditions. The results indicate that THPP quenched the intrinsic fluorescence of lysozyme via a static quenching procedure. The binding constant KA between THPP and lysozyme was 5.97×104 L/mol at 291 K. According to the thermodynamic parameters, it was obtained that hydrophobic was a main acting force between THPP and lysozyme. The presence of Fe²⁺,Fe³⁺,Cu²⁺,Mg²⁺,Ca²⁺and Zn²⁺ did not affect the binding constant of THPP and lysozyme. According to Frster’s nonradiative energy transfer theory, the distance between THPP and lysozyme was 3.35nm. The synchronous fluorescence spectra reveal that the vicinity of tryptophan becomes more hydrophobicity with the increase of THPP.

Key words: meso-tetra(4-hydroxyphenyl)porphyrin (THPP), lysozyme, fluorescence quenching