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Spectroscopy
Volume 21, Issue 4, Pages 235-243
http://dx.doi.org/10.1155/2007/503537

Spectroscopic studies on the interaction of hypocrellin A with myoglobin

J. H. Zhou,1 X. H. Wu,1 C. Yang,3 X. T. Gu,1 L. Zhou,2 K. X. Song,1 Y. Y. Feng,1,4 and J. Shen1

1Analysis & Testing Center, Jiangsu Engineering Research Center for Bio-medical Function Materials, Nanjing Normal University, Nanjing, 210097, China
2School of Life Science, Nanjing Normal University, Nanjing, 210097, China
3Department for intensive instruction, Nanjing Normal University, Nanjing, 210097, China
4Analysis & Testing Center, Jiangsu Engineering Research Center for Bio-medical Function Materials, Nanjing Normal University, 122 Ninghai Road, Nanjing, Nanjing, Jiangsu, 210097, China

Copyright © 2007 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Experimental results of UV-visible absorption spectroscopy and fluorescence spectroscopy indicate that hypocrellin A, which has been studied in photodynamic therapy, can interact with the surface of myoglobin through hydrophobic forces, and form a complex. Based on the Stern–Volmer equation, the quenching constants of the process can be calculated to be 4.81×1012 L mol−1 s−1 (t=25°C) and 4.54×1012 L mol−1 s−1 (t=42°C) respectively, and the binding constant is 5.53×104 M−1 (t=25°C), while the binding sites is 0.94 (t=25°C). In addition, Electron paramagnetic resonance and fluorescence spectroscopic analysis suggests that that the quenching mechanism of the interaction process occurs through the electron transfer between hypocrellin A and myoglobin.