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.
Vol. 8, Iss. 5 Virtual Journal for Biomedical Optics
Letícia Bonfante Sicchieri, Andrea Moreira Monteiro, Ricardo Elgul Samad, Amando Siuiti Ito, Antonio Martins Figueiredo Neto, Nilson Dias Vieira, Magnus Gidlund, and Lilia Coronato Courrol, "Study of Tryptophan Lifetime Fluorescence Following Low-Density Lipoprotein Modification," Appl. Spectrosc. 67, 379-384 (2013)