title: Mass Spectrometric and Spectrofluorometric Studies of the Interaction of Aristolochic Acids with Proteins.
abstract: Aristolochic acid (AA) is a potent carcinogen and nephrotoxin and is associated with the development of "Chinese herb nephropathy" and Balkan endemic nephropathy. Despite decades of research, the specific mechanism of the observed nephrotoxicity has remained elusive and the potential effects on proteins due to the observed toxicity of AA are not well-understood. To better understand the pharmacotoxicological features of AA, we investigated the non-covalent interactions of AA with proteins. The protein-binding properties of AA with bovine serum albumin (BSA) and lysozyme were characterized using spectrofluorometric and mass spectrometric (MS) techniques. Moreover, the protein-AA complexes were clearly identified by high-resolution MS analyses. To the best of our knowledge, this is the first direct evidence of non-covalently bound protein-AA complexes. An analysis of the spectrofluorometric data by a modified Stern-Volmer plot model also revealed that both aristolochic acid I (AAI) and aristolochic acid II (AAII) were bound to BSA and lysozyme in 1:1 stoichiometries. A significantly stronger protein binding property was observed in AAII than in AAI as evidenced by the spectrofluorometric and MS analyses, which may explain the observed higher mutagenicity of AAII.
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
authors.forename: Qin
authors.initials: Q
authors.lastname: Hu
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
authors.forename: Wan
authors.initials: W
authors.lastname: Chan
mesh_terms: D000818:Animals; D034341:Aristolochic Acids / Q000737:chemistry* / Q000378:metabolism; D002417:Cattle; D009113:Muramidase / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D012710:Serum Albumin, Bovine / Q000737:chemistry* / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D034341:Aristolochic Acids; D012710:Serum Albumin, Bovine; C000228:aristolochic acid I; C042310:aristolochic acid II; D009113:Muramidase