Binding studies of porphyrins to human serum albumin using affinity capillary electrophoresis

Yongsheng Ding, Bingcheng Lin, Carmen W K HUIE*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

46 Citations (Scopus)


The present work demonstrates that affinity capillary electrophoresis (ACE) can be employed as a valuable and powerful tool for studying the interactions between porphyrins and proteins in biological and biomedical research, such as the development of porphyrins and related compounds as efficient and selective photosensitizers in the photodynamic therapy of cancers. Binding constants of human serum albumin (HSA) to four biological porphyrins (uroporphyrin I, heptacarboxylporphyrin, coproporphyrin I, protoporphyrin IX), which possess a wide range of hydrophobicity, were estimated by ACE. Based on 1:1 molecular association between these individual porphyrins and HSA, the change of the electrophoretic mobility of HSA as a function of porphyrin concentration in the run buffer was measured and the binding constants were calculated from the slope of the Scatchard plots. The binding constant values were found to be 8.80 ± 0.51 × 104 M-1, 2.39 ± 0.16 × 105 M-1, 1.61 ± 0.11 × 106 M-1, and 9.34 ± 0.30 × 106 M-1 for uroporphyrin I, heptacarboxylporphyrin, coproporphyrin I, and protoporphyrin IX, respectively, and most of these results are in good agreement with those reported in the literature using conventional methods for binding measurements. Additionally, experimental binding constant data obtained using ACE was found to exhibit very good correlation with theoretical hydrophobicity values calculated using the Rekker's hydrophobic fragmental constant method, thus further supporting the hypothesis that the hydrophobicity of the porphyrin side chains play an important role in governing the hydrophobic interaction of porphyrins with serum proteins such as HSA.

Original languageEnglish
Pages (from-to)2210-2216
Number of pages7
Issue number11
Publication statusPublished - 2001

Scopus Subject Areas

  • Analytical Chemistry
  • Biochemistry
  • Clinical Biochemistry

User-Defined Keywords

  • Affinity capillary electrophoresis
  • Binding studies
  • Human serum albumin
  • Porphyrins


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