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Amino-acid solvation structure in transmembrane helices from molecular dynamics simulations
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för biokemi och biofysik.ORCID-id: 0000-0002-2734-2794
2006 (Engelska)Ingår i: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 91, nr 12, s. 4450-4463Artikel i tidskrift (Refereegranskat) Published
Ort, förlag, år, upplaga, sidor
2006. Vol. 91, nr 12, s. 4450-4463
Nyckelord [en]
Amino Acids/*chemistry, Cell Membrane, Computer Simulation, Hydrogen Bonding, Membrane Proteins/*chemistry, Models; Molecular, Protein Folding, Protein Structure; Secondary, Water/chemistry
Identifikatorer
URN: urn:nbn:se:su:diva-11255DOI: 10.1529/biophysj.106.092767PubMedID: 17012325OAI: oai:DiVA.org:su-11255DiVA, id: diva2:177774
Tillgänglig från: 2008-01-10 Skapad: 2008-01-10 Senast uppdaterad: 2022-02-25Bibliografiskt granskad
Ingår i avhandling
1. Solvation properties of proteins in membranes
Öppna denna publikation i ny flik eller fönster >>Solvation properties of proteins in membranes
2009 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Knowledge about the insertion and stabilization of membrane proteins is a key step towards understanding their function and enabling membrane protein design. Transmembrane helices are normally quite hydrophobic to insert efficiently, but there are many exceptions with unfavorable polar or titratable residues. Since evolutionary conserved these amino acids are likely of paramount functional importance, e.g. the four arginines in the S4 voltage sensor helix of voltage-gated ion channels. This has lead to vivid discussion about their conformation, protonation state and cost of insertion. To address such questions, the main focus of this thesis has been membrane protein solvation in lipid bilayers, evaluated using molecular dynamics simulations methods.

A main result is that polar and charged amino acids tend to deform the bilayer by pulling water/head-groups into the hydrophobic core to keep their hydrogen bonds paired, thus demonstrating the adaptiveness of the membrane to allow specific and quite complex solvation. In addition, this retained hydration suggests that the solvation cost is mainly due to entropy, not enthalpy loss. To further quantify solvation properties, free energy profiles were calculated for all amino acids in pure bilayers, with shapes correlating well with experimental in vivo values but with higher magnitudes. Additional profiles were calculated for different protonation states of the titratable amino acids, varying lipid composition and with transmembrane helices present in the bilayer. While the two first both influence solvation properties, the latter seems to be a critical aspect. When the protein fraction in the models resemble biological membranes, the solvation cost drops significantly - even to values compatible with experiment.

In conclusion, by using simulation based methods I have been able to provide atomic scale explanations to experimental results, and in particular present a hypothesis for how the solvation of charged groups occurs.

Ort, förlag, år, upplaga, sidor
Stockholm: Department of Biochemistry and Biophysics, Stockholm University, 2009. s. 62
Nyckelord
membrane protein, lipid bilayer, free energy, solvation, insertion, molecular dynamics simulations, protein mass fraction
Nationell ämneskategori
Teoretisk kemi
Forskningsämne
biokemi
Identifikatorer
urn:nbn:se:su:diva-27437 (URN)978-91-7155-856-5 (ISBN)
Disputation
2009-06-12, Magnelisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 12, Stockholm, 13:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2009-05-22 Skapad: 2009-05-04 Senast uppdaterad: 2022-02-25Bibliografiskt granskad

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Johansson, Anna CVLindahl, Erik

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Biophysical Journal

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