title: Cigarette smoke induces p-benzoquinone-albumin adduct in blood serum: Implications on structure and ligand binding properties.
abstract: Earlier we had reported that irrespective of the source cigarette smoke (CS) contains substantial amounts of p-benzosemiquinone, which is readily converted to p-benzoquinone (p-BQ) by disproportionation and oxidation by transition metal containing proteins. Here we show that after CS-exposure, p-BQ-protein adducts are formed in the lungs as well as serum albumin of guinea pigs. We also show that serum of human smokers contains p-BQ-albumin adduct. It is known that human serum albumin (HSA) plays a very important role in binding and transport of a variety of ligands, including fatty acids and drugs. We show in vitro that p-BQ forms covalent adducts with free amino groups of all twenty amino acids as well as ɛ-amino groups of lysine residues of HSA in a concentration dependent manner. When HSA is incubated with p-BQ in the molar ratio of 1:1, the number of p-BQ incorporated is 1. At the molar ratio of 1:60, the number of p-BQ incorporated is 40. The formation of HSA-p-BQ adduct has been demonstrated by absorption spectroscopy, MALDI-MS and MALDI-TOF-TOF-MS analyses. Upon complexation with p-BQ, the secondary structure and conformation of HSA are altered, as evidenced by steady state and time-resolved fluorescence, circular dichroism, 8-anilino-1-napthalenesulfonic acid binding and differential scanning calorimetry. Alteration of the structure and conformation of HSA results in impairment of its ligand binding properties with respect to myristic acid, quercitin and paracetamol. This might be one of the reasons why transport and distribution of lipids and drugs are impaired in smokers.
authors.affiliation: Department of Biotechnology and Dr. B. C. Guha Centre for Genetic Engineering & Biotechnology, Calcutta University College of Science, 35, Ballygunge Circular Road, Kolkata 700019, India.
authors.forename: Arunava
authors.initials: A
authors.lastname: Ghosh
authors.forename: Aparajita
authors.initials: A
authors.lastname: Choudhury
authors.forename: Archita
authors.initials: A
authors.lastname: Das
authors.forename: Nabendu S
authors.initials: NS
authors.lastname: Chatterjee
authors.forename: Tanusree
authors.initials: T
authors.lastname: Das
authors.forename: Rukhsana
authors.initials: R
authors.lastname: Chowdhury
authors.forename: Koustubh
authors.initials: K
authors.lastname: Panda
authors.forename: Rajat
authors.initials: R
authors.lastname: Banerjee
authors.forename: Indu B
authors.initials: IB
authors.lastname: Chatterjee
mesh_terms: D000082:Acetaminophen / Q000378:metabolism; D000328:Adult; D000818:Animals; D016227:Benzoquinones / Q000097:blood*; D002152:Calorimetry, Differential Scanning; D002942:Circular Dichroism; D006168:Guinea Pigs; D006801:Humans; D008168:Lung / Q000378:metabolism; D008297:Male; D011485:Protein Binding; D011487:Protein Conformation; D011794:Quercetin / Q000378:metabolism; D012709:Serum Albumin / Q000378:metabolism*; D012907:Smoking / Q000097:blood*; D013050:Spectrometry, Fluorescence; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013056:Spectrophotometry, Ultraviolet
chemical_list: D016227:Benzoquinones; D012709:Serum Albumin; D000082:Acetaminophen; C004532:quinone; D011794:Quercetin