IR spectroscopy analysis of pancreatic lipase-related protein 2 interaction with phospholipids: 1. Discriminative recognition of mixed micelles versus liposomes

• Published in: Chemistry and physics of lipids 2018-03, Vol.211, p.52-65
• Main Authors: Mateos-Diaz, Eduardo, Bakala N’Goma, Jean-Claude, Byrne, Deborah, Robert, Sylvie, Carrière, Frédéric, Gaussier, Hélène
• Format: Article
• Language: English
• Subjects: Biochemistry; Biochemistry, Molecular Biology; Biophysics; Enzyme; FTIR spectroscopy; Life Sciences; Lipid digestion; Lipids; Lipolysis; Phospholipase
• ISSN: 0009-3084; 1873-2941
• DOI: 10.1016/j.chemphyslip.2017.02.005

[Display omitted] •Comparative IR analysis of phospholipid (DPPC)-bile salt (NaTDC) micelles and DPPC vesicles (MLV and LUV).•IR analysis of pancreatic lipase-related protein 2 (PLRP2) interaction with DPPC-NaTDC micelles and DPPC vesicles.•Correlation between IR analysis and enzyme activity of PLRP2 on DPPC-NaTDC micelles but not vesicles.•Effects of PLRP2-micelle interaction on DPPC acyl chains, interfacial carbonyl groups and polar head groups. Guinea pig pancreatic lipase-related protein 2 (GPLRP2) is an interesting model enzyme that can hydrolyze a large set of acylglycerols in vitro but displays however some selectivity depending on the supramolecular structure of substrate and the presence of surfactants like bile salts. We showed that GPLRP2 hydrolyzes 1,2-dipalmitoyl phosphatidylcholine (DPPC) present in mixed micelles with sodium taurodeoxycholate (NaTDC) but not in multilamellar (MLV) and large unilamellar (LUV) vesicles of DPPC. After characterization of these lipid aggregates by dynamic light scattering (DLS), the discriminative recognition of DPPC in DPPC/NaTDC micelles versus MLV and LUV by an inactive variant (S152G) of GPLRP2 to avoid the effect of substrate hydrolysis was investigated using Fourier transform infrared spectroscopy (FTIR). IR spectra were recorded after hydrogen/deuterium exchange, at pD 6 and various temperatures to study phase transitions. We analyzed the methylene asymmetric stretching (ν(CH2)as), the carbonyl stretching (ν(CO)) and the composite polar head-group vibration bands, first to characterized differences in DPPC micelles and vesicles, and second to estimate the degree of interaction of GPLRP2 S152G with phospholipid. Our results indicate that a significant interaction between GPLRP2 S152G and DPPC is only observed when NaTDC is added to the system to form micelles and this can be explained by the different organization of DPPC in mixed micelles compared to lamellar vesicles (higher hydration of polar head, higher mobility of alkyl chains) that favors GPLRP2 penetration into the phospholipid layer.