Capillary electrochromatography and quartz crystal microbalance, valuable techniques in the study of heparin - lipoprotein interactions

KATRIINA LIPPONEN; YI LIU; PATRICIA WANDA STEGE; KATARIINA Ö ÖRNI; PETRI T. KOVANEN; MARJA-LIISA RIEKKOLA

ANALYTICAL BIOCHEMISTRY

ACADEMIC PRESS INC ELSEVIER SCIENCE

Año: 2012 vol. 424 p. 71 - 78

0003-2697

Atherosclerosis is initiated when lipoproteins bind to proteoglycans (PGs) in arterialwall. The binding is mediated by apolipoprotein apoB-100 and/or apoE, both of whichhave binding affinity toward heparin. We developed covalently bound heparincoatings for APTES-modified silica capillary and SiO2 chips and carried out capillaryelectrochromatography (CEC) and quartz crystal microbalance (QCM) studies on theinteractions of heparin with selected peptide fragments of apoB-100 and apoE and, forCEC, also with low and high density lipoproteins (LDL and HDL), the latter with andwithout apoE. The peptides are known to mediate interactions of HDL and LDL witharterial PGs. Interactions and affinities were expressed in CEC as retention factorsand reduced mobilities and in continuous flow QCM technique as affinity constants.Both techniques showed heparin interactions to be stronger with apoB-100 peptidethan with apoE peptide fragment, and they confirmed that the sulfate groups inheparin play an especially important role in interactions with apoB-100 peptidefragment. In addition, CEC confirmed the importance of sulfate groups of heparin ininteractions between heparin and LDL and between heparin and apoE-containingHDL. CEC and QCM acted as excellent platforms to mimic these biologicallyimportant interactions, with small sample and reagent consumption.