Translocation mechanism of long sugar chains across the maltoporin membrane channel

Dutzler, Raimund and Schirmer, Tilman and Karplus, Martin and Fischer, Stefan. (2002) Translocation mechanism of long sugar chains across the maltoporin membrane channel. Structure: with folding and design, Vol. 10, H. 9. pp. 1273-1284.

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Official URL: http://edoc.unibas.ch/dok/A5258258

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Maltoporin allows permeation of long maltodextrin chains. It tightly binds the amphiphilic sugar, offering both hydrophobic interactions with a helical lane of aromatic residues and H bonds with ionic side chains. The minimum-energy path of maltohexaose translocation is obtained by the conjugate peak refinement method, which optimizes a continuous string of conformers without applying constraints. This reveals that the protein is passive while the sugar glides screw-like along the aromatic lane. Near instant switching of sugar hydroxyl H bond partners results in two small energy barriers (of approximately 4 kcal/mol each) during register shift by one glucosyl unit, in agreement with a kinetic analysis of experimental dissociation rates for varying sugar chain lengths. Thus, maltoporin functions like an efficient translocation "enzyme," and the slow rate of the register shift (approximately 1/ms) is due to high collisional friction.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Structural Biology & Biophysics > Structural Biology (Schirmer)
UniBasel Contributors:Schirmer, Tilman
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Current Biology
Note:Publication type according to Uni Basel Research Database: Journal article
Last Modified:07 Aug 2015 12:05
Deposited On:22 Mar 2012 13:20

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