Potential protein toxicity of synthetic pigments: binding of poncean S to human serum albumin.
Using various methods, e.g., spectrophotometry, circular dichroism, and isothermal titration calorimetry, the interaction of poncean S (PS) with human serum albumin (HSA) was characterized at pH 1.81, 3.56, and 7.40 using the spectral correction technique, and Langmuir and Temkin isothermal models. The consistency among results concerning, e.g., binding number, binding energy, and type of binding, showed that ion pair electrostatic attraction fixed the position of PS in HSA and subsequently induced a combination of multiple noncovalent bonds such as H-bonds, hydrophobic interactions, and van der Waals forces. Ion pair attraction and H-bonds produced a stable PS-HSA complex and led to a marked change in the secondary structure of HSA in acidic media. The PS-HSA binding pattern and the process of change in HSA conformation were also investigated. The potentially toxic effect of PS on the transport function of HSA in a normal physiological environment was analyzed. This work provides a useful experimental strategy for studying the interaction of organic substances with biomacromolecules, helping us to understand the activity or mechanism of toxicity of an organic compound.
Gao
Hong-Wen
HW
State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Shanghai 200092, PR China. hwgao@mail.tongji.edu.cn
Xu
Qing
Q
Chen
Ling
L
Wang
Shi-Long
SL
Wang
Yuan
Y
Wu
Ling-Ling
LL
Yuan
Yuan
Y
D001391:Azo Compounds / Q000737:chemistry*; D001665:Binding Sites; D004396:Coloring Agents / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D011485:Protein Binding; D011487:Protein Conformation; D012709:Serum Albumin / Q000737:chemistry* / Q000648:ultrastructure*; D018675:Toxicity Tests
D001391:Azo Compounds; D004396:Coloring Agents; D012709:Serum Albumin; C032756:ponceau S