title: Comparison of the α and β isomeric forms of the detergent n-dodecyl-D-maltoside for solubilizing photosynthetic complexes from pea thylakoid membranes.
abstract: Mild non-ionic detergents are indispensable in the isolation of intact integral membrane proteins and protein-complexes from biological membranes. Dodecylmaltoside (DM) belongs to this class of detergents being a glucoside-based surfactant with a bulky hydrophilic head group composed of two sugar rings and a non-charged alkyl glycoside chain. Two isomers of this molecule exist, differing only in the configuration of the alkyl chain around the anomeric center of the carbohydrate head group, axial in α-DM and equatorial in β-DM. In this paper, we have investigated the solubilizing properties of α-DM and β-DM on the isolation of photosynthetic complexes from pea thylakoids membranes maintaining their native architecture of stacked grana and stroma lamellae. Exposure of these stacked thylakoids to a single step treatment with increasing concentrations (5-100mM) of α-DM or β-DM resulted in a quick partial or complete solubilization of the membranes. Regardless of the isomeric form used: 1) at the lowest DM concentrations only a partial solubilization of thylakoids was achieved, giving rise to the release of mainly small protein complexes mixed with membrane fragments enriched in PSI from stroma lamellae; 2) at concentrations above 30mM a complete solubilization occurred with the further release of high molecular weight protein complexes identified as dimeric PSII, PSI-LHCI and PSII-LHCII supercomplexes. However, at concentrations of detergent which fully solubilized the thylakoids, the α and β isomeric forms of DM exerted a somewhat different solubilizing effect on the membranes: higher abundance of larger sized PSII-LHCII supercomplexes retaining a higher proportion of LHCII and lower amounts of PSI-LHCI intermediates were observed in α-DM treated membranes, reflecting the mildness of α-DM compared with its isomer. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial.
authors.affiliation: Department of Materials Science and Chemical Engineering - BioSolar Lab, Politecnico di Torino, Alessandria, Italy. cristina.pagliano@polito.it
authors.forename: Cristina
authors.initials: C
authors.lastname: Pagliano
authors.forename: Simone
authors.initials: S
authors.lastname: Barera
authors.forename: Fabiana
authors.initials: F
authors.lastname: Chimirri
authors.forename: Guido
authors.initials: G
authors.lastname: Saracco
authors.forename: James
authors.initials: J
authors.lastname: Barber
mesh_terms: D002850:Chromatography, Gel; D003902:Detergents / Q000494:pharmacology*; D005960:Glucosides / Q000494:pharmacology*; D007536:Isomerism; D018532:Pisum sativum / Q000378:metabolism*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D012995:Solubility; D020524:Thylakoids / Q000737:chemistry*
chemical_list: D003902:Detergents; D005960:Glucosides; D045322:Photosynthetic Reaction Center Complex Proteins; C040358:dodecyl maltoside