title: Study of tryptophan lifetime fluorescence following low-density lipoprotein modification.
abstract: In this paper we report the effects of the irradiation of low-density lipoprotein (LDL) by ultra-short laser pulses to obtain in vitro alterations mimicking proatherogenic modifications occurring in vivo in LDL. The modifications by metallic ions (copper and iron) and ultra-short laser pulses were studied by fluorescence steady state and time-resolved lifetime measurements. The results demonstrate that the modifications caused by ultra-short laser pulses and by iron affect the tryptophan residues of apolipoprotein B-100 (Apo-B), slightly decreasing fluorescent lifetimes, with almost no modifications in pre-exponential factors, indicating preservation of structural properties around the fluorophore. On the other hand, oxidation by copper strongly affects the Apo-B protein associated with LDL. We describe a fast, inexpensive, and nondestructive fluorescence-based method that is readily accessible to provide the LDL particle characterization.
authors.affiliation: Centro de Lasers e Aplicações, Instituto de Pesquisas Energéticas e Nucleares-Comissão Nacional de Energia Nuclear, Avenida Lineu Prestes 2242, São Paulo-SP, 05508, Brazil.
authors.forename: Letícia Bonfante
authors.initials: LB
authors.lastname: Sicchieri
authors.forename: Andrea Moreira
authors.initials: AM
authors.lastname: Monteiro
authors.forename: Ricardo Elgul
authors.initials: RE
authors.lastname: Samad
authors.forename: Amando Siuiti
authors.initials: AS
authors.lastname: Ito
authors.forename: Antonio Martins Figueiredo
authors.initials: AM
authors.lastname: Neto
authors.forename: Nilson Dias
authors.initials: ND
authors.lastname: Vieira
authors.forename: Magnus
authors.initials: M
authors.lastname: Gidlund
authors.forename: Lilia Coronato
authors.initials: LC
authors.lastname: Courrol
mesh_terms: D016880:Anisotropy; D053299:Apolipoprotein B-100 / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D006801:Humans; D007501:Iron / Q000737:chemistry; D007834:Lasers; D015227:Lipid Peroxidation; D008077:Lipoproteins, LDL / Q000737:chemistry*; D010084:Oxidation-Reduction; D015203:Reproducibility of Results; D013050:Spectrometry, Fluorescence / Q000379:methods*; D014364:Tryptophan / Q000032:analysis / Q000737:chemistry*
chemical_list: D053299:Apolipoprotein B-100; D008077:Lipoproteins, LDL; D003300:Copper; D014364:Tryptophan; D007501:Iron