Size is a major determinant of dissociation and denaturation behaviour of reconstituted high-density lipoproteins

Publisher Website
Google Scholar
Abstract
Lipid-free apolipoprotein A-I (apoA-I) and A-IMilano (A-IM) were compared for their denaturation behaviour by running across transverse gradients of a chaotrope, urea, and of a ionic detergent, SDS. For both apo A-I and monomeric apoA-IM in the presence of increasing concentrations of urea the transition from high to low mobility had a sigmoidal course, whereas for dimeric A-IM/A-IM a non-sigmoidal shape was observed. The co-operativity of the unfolding process was lower for dimeric A-IM/A-IM than for apoA-I or for monomeric apoA-IM. A slightly higher susceptibility to denaturation was observed for dimeric A-IM/A-IM than for monomeric apoA-IM. A similar behaviour of A-IM/A-IM versus apoA-IM was observed in CD experiments. Large- (12.7/12.5nm) and small- (7.8nm) sized reconstituted high-density lipoproteins (rHDL) containing either apoA-I or A-IM/A-IM were compared with respect to their protein—lipid dissociation behaviour by subjecting them to electrophoresis in the presence of urea, of SDS and of a non-ionic detergent, Nonidet P40. A higher susceptibility to dissociation of small-sized versus large-sized rHDL, regardless of the apolipoprotein component, was observed in all three instances. Our data demonstrate that the differential plasticity of the various classes of rHDL is a function of their size; the higher stability of 12.5/12.7nm rHDL is likely connected to the higher number of protein—lipid and lipid—lipid interactions in larger as compared with smaller rHDL.

This publication has 32 references indexed in Scilit: