Lipoprotein (a) Particles Characterization by Dynamic Light Scattering
Valentina Pasquetto
Department of Molecular Medicine, Unit of Immunology and General Pathology, University of Pavia, Pavia, Italy.
Alice Santonastaso
Department of Molecular Medicine, Unit of Immunology and General Pathology, University of Pavia, Pavia, Italy.
Stefania Grandi
Department of Chemistry, University of Pavia, Pavia, Italy and Nano Analysis and Materials (NAM) S.r.l., Pavia, Italy.
Giuseppe Derosa
Department of Internal Medicine and Therapeutics, University of Pavia, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy and Laboratory of Molecular Medicine, University of Pavia, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy.
Angela D'Angelo
Department of Internal Medicine and Therapeutics, University of Pavia, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy and Laboratory of Molecular Medicine, University of Pavia, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy.
Claudia Scotti *
Department of Molecular Medicine, Unit of Immunology and General Pathology, University of Pavia, Pavia, Italy.
*Author to whom correspondence should be addressed.
Abstract
Lp(a) is a novel cardiovascular risk factor resembling an LDL particle. It includes a copy of apolipoprotein (a) [apo(a)], whose molecular weight is dependent on the number of genetically encoded kringle IV type 2 (KIV-2) repeats and inversely related with Lp(a) plasma concentration and risk. The reason for this inverse relationship is unclear and, particularly, there are no data regarding the size of Lp(a) particles carrying apo(a) with different molecular weights. The aim of the present work was to explore if a relationship existed between apo(a) molecular weight and particles size in Lp(a) samples carrying 20, 25 and 28 KIV-2 repeats (K20, K25 and K28, respectively). Dynamic Light Scattering (DLS) measurements were performed on affinity-purified Lp(a). A preliminary finding was that particles were typically distributed into three different size groups instead of the single one expected. No difference in average particle size between Lp(a) carrying different apo(a) isoforms was found. However, the percentage of medium-sized particles in each sample was found to be inversely related to the number of KIV-2 repeats (R2=0.99), with a clear predominance in K20 (58.53%). These data deserve further investigations, as they might be potentially relevant to explain the pathogenic role of low molecular weight Lp(a) isoforms.
Keywords: Lipoprotein (a), particle size, atherosclerosis, plasma, Zeta-sizer.