Journal of Chinese Pharmaceutical Sciences

• Original articles • Previous Articles     Next Articles

Site- and orientation-specific binding of hematoporphyrin monomethyl ether to human serum albumin revealed by single spectral kinetic parameter

Luyong Zhang, Miao Zhang, Haixia Qiu, Ying Gu*, Jingquan Zhao*   

  1. 1. Institute for Food and Cosmetics Control, National Institutes for Food and Drug Control, Beijing 100050, China
    2. Department of Pharmaceutical Care, Chinese PLA General Hospital, Beijing 100853, China
    3. Department of Laser Medicine, Chinese PLA General Hospital, Beijing 100853, China
    4. Key Laboratory of Photochemistry, Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
  • Received:2013-06-24 Revised:2013-08-02 Online:2013-11-15 Published:2014-01-22
  • Contact: Ying Gu*, Jingquan Zhao*


Interaction of a drug molecule with human serum albumin (HSA) is usually studied by fluorescence responses of the ligand or/and the single tryptophan residue (Trp-214) of the protein, but qualitative spectral information may lead to multiple conclusions. In this work, we report a study on the interaction of hematoporphyrin monomethyl ether (HMME) with human serum albumin (HSA), using the environment-sensitive spectra of HMME and reaction-induced fluorescence response of Trp-214. Particularly, the single kinetic parameter, the linear slope, was derived from the concentration-dependent absorbance or fluorescence of HMME in a certain solvent. A quantitative change in the slope at [HMME]/[HSA] = 1:1 clearly demonstrated a specific binding of HMME to site I. The microenvironment in site I may be comparable to that in DMSO solvent, because of the similarity of the slope. Linear correlation of the fluorescence to the absorbance of HMME in site I indicates that the energy transfer is not responsible for Trp-214 fluorescence quenching but an electron transfer may be possible. In addition, much higher rate observed for the binding of HMME or 2-taurine-substituted HB (THB) with HSA than that of hypocrellin B was due to the electrostatic attraction under physiological condition.

Key words: Human serum albumin, Photosensitizing agent, Specific binding, Dimensional fitting, Electrostatic driving

CLC Number: