Characterization of the photoproducts of protoporphyrin IX bound to human serum albumin and immunoglobulin G

Brancaleon, L., Magennis, S. W., Samuel, I. D. W., Namdas, E., Lesar, A. and Moseley, H. (2004) Characterization of the photoproducts of protoporphyrin IX bound to human serum albumin and immunoglobulin G. Biophysical Chemistry, 109 3: 351-360. doi:10.1016/j.bpc.2003.12.008


Author Brancaleon, L.
Magennis, S. W.
Samuel, I. D. W.
Namdas, E.
Lesar, A.
Moseley, H.
Title Characterization of the photoproducts of protoporphyrin IX bound to human serum albumin and immunoglobulin G
Journal name Biophysical Chemistry   Check publisher's open access policy
ISSN 0301-4622
1873-4200
Publication date 2004-06
Sub-type Article (original research)
DOI 10.1016/j.bpc.2003.12.008
Volume 109
Issue 3
Start page 351
End page 360
Total pages 10
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Language eng
Abstract Clinically useful photosensitisers (PSs) are likely bound to subcellular and molecular targets during phototherapy. Binding to a macromolecule has the potential to change the photophysical and photochemical characteristics of the PSs that are crucial for their phototoxicity and cell-killing activity. We investigated the effects of binding of a specific PS (protoporphyrin IX or PPIX) to two proteins, human serum albumin (HSA) and a commercially available immunoglobulin (IgG). These two proteins provide two different environments for PPIX. The albumin binds PPIX in hydrophobic binding sites located in subdomain IIA and IIIA, conversely IgG leaves PPIX exposed to the solvent. We show that photophysical parameters such as emission maxima and fluorescence lifetime depend on the binding site. Our results indicate that the different binding site yields very different rates of formation of photoproducts (more than three times higher for PPIX bound to HSA than to IgG) and that different mechanisms of formation may be occurring. Our characterization shows the relevance of protein binding for the photochemistry and ultimately the phototoxicity of PSs.
Keyword Human serum albumin
Immunoglobulin G
Protoporphyrin IX
Fluorescence spectroscopy
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Mathematics and Physics
 
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Created: Wed, 09 Mar 2011, 13:16:59 EST