The Modification of Tetraether Lipids from the Archeon Sulfolobus Acidocaldarius and Characterisation of their Monolayer Behaviour


Nico Harbach1, Norbert Hampp2, Daniel Rhinow2, and Udo Bakowsky1

1Department of Pharmaceutical Technology and Biopharmaceutics, University of Marburg, Ketzerbach 63, 35037 Marburg, Germany

2Faculty of Chemistry, University of Marburg, Hans-Meerwein-Straße, 35032 Marburg, Germany

e-mail: nico@staff.uni-marburg.de

URL: http://web.uni-marburg.de/iptb/institut/akbakowsky/NicoHarbach.html

 

The archaebacterium Sulfolobus Acidocaldarius has no cell wall and prefers living in pH values from 1-2 and temperatures from 80-90 C. This attribute is due to its stabile lipid membrane. It consists of tetraether lipids, which are, other than regular phospholipids, built from two macrocyclic tetraethers, having pairs of bifunctional C40 isoprenoid chains, with a 16,16'-biphytanyl skeleton, that differ by as much as four cyclopentane rings. The absence of double bonds in the hydrocarbon chain and the ether bonds to the glycerols guarantee the resistance towards hydrolytic, oxidative and other (bio)chemical attack. These extreme stable lipids are able to form self assembled monolayers. In this study, we examined principal behaviour of tetraether lipids and mixtures of it with classic phospholipids like DSPE and DPPC in order to create new biohybrid materials. In a pre-examination, we investigated the crude tetraether lipid, which we modified chemically, with film balance and AFM. We designed monolayers, combined them with gold nanoparticles, DNA or bacteriorhodopsin and examined their phase behaviour. The main lipid component in sulfolobus acidocaldarius is the glycerol dialkyl nonitol tetraether (GDNT). We extracted, purified and modified GDNT chemically for the use in modified monolayers. The film behaviour of this new GDNT derivative was analysed with classically film balance measurements, AFM, and SEM. Additionally, self assemblied monolayers of the GDNT thiol-derivative on gold surface were prepared and further treated with laser ablation to generate surface structures within the monolayer. The diffusion behaviour of other lipids into the supported tetraether lipid film was investigated with AFM and SEM.