In situ monitoring of galactolipid digestion by infrared spectroscopy in both model micelles and spinach chloroplasts.
Chem Phys Lipids
; 252: 105291, 2023 05.
Article
en En
| MEDLINE
| ID: mdl-36918051
Galactolipids are the main lipids from plant photosynthetic membranes and they can be digested by pancreatic lipase related protein 2 (PLRP2), an enzyme found in the pancreatic secretion in many animal species. Here, we used transmission Fourier-transform infrared spectroscopy (FTIR) to monitor continuously the hydrolysis of galactolipids by PLRP2, in situ and in real time. The method was first developed with a model substrate, a synthetic monogalactosyl diacylglycerol with 8-carbon acyl chains (C8-MGDG), in the form of mixed micelles with a bile salt, sodium taurodeoxycholate (NaTDC). The concentrations of the residual substrate and reaction products (monogalactosylmonoglyceride, MGMG; monogalactosylglycerol, MGG; octanoic acid) were estimated from the carbonyl and carboxylate vibration bands after calibration with reference standards. The results were confirmed by thin layer chromatography analysis (TLC) and specific staining of galactosylated compounds with thymol and sulfuric acid. The method was then applied to the lipolysis of more complex substrates, a natural extract of MGDG with long acyl chains, micellized with NaTDC, and intact chloroplasts isolated from spinach leaves. After a calibration performed with α-linolenic acid, the main fatty acid (FA) found in plant galactolipids, FTIR allowed quantitative measurement of chloroplast lipolysis by PLRP2. A full release of FA from membrane galactolipids was observed, that was not dependent on the presence of bile salts. Nevertheless, the evolution of amide vibration band in FTIR spectra suggested the interaction of membrane proteins with NaTDC and lipolysis products.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Galactolípidos
/
Micelas
Límite:
Animals
Idioma:
En
Revista:
Chem Phys Lipids
Año:
2023
Tipo del documento:
Article
País de afiliación:
Francia
Pais de publicación:
Irlanda