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Interactions of Ulva linza zoospores with arginine-rich oligopeptides
Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
School of Biosciences, University of Birmingham, Birmingham, United Kingdom.
Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
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(English)Manuscript (Other academic)
Abstract [en]

We recently reported on the strong interactions of Ulva linza zoospores with an arginine-rich oligopeptide self-assembled monolayer (SAM) [Biofouling 24:303-312 (2008)], where the arginine-rich peptide induced not only very high settlement but also a form of abnormal settlement, or “pseudo-settlement”, where spores do not go through the normal behaviours of surface exploration, adhesive exocytosis and flagella loss. Further, it was demonstrated that both the total settlement and the fraction of anomalously settled spores were related to the surface density of the arginine-rich peptide.Here we present a further investigation of the interactions of Ulva zoospores with a set of oligomeric de novo designed arginine-rich peptides, specifically aimed to test the effect of peptide primary structure on the interaction. Via variations in the peptide length and by permutations in the amino acid sequences, we gain further insight into the spore-surface interactions. The interpretation of the biological assays is supported by physicochemical characterization of the SAMs using infrared spectroscopy, ellipsometry and contact angle measurements. Results confirm the importance of arginine residues for the anomalous settlement, and we found that settlement is modulated by variations in the peptide primary structure. To elucidate the causes of the anomalous settlement and the possible relation to peptide-membrane interactions, we also compared the settlement of the “naked” Ulva zoospores (which lack a cell wall), with the settlement of Navicula diatoms (which are surrounded by a silica shell), onto the peptide SAMs. Cationic SAMs do not particularly affect adhesion or viability of diatoms, suggesting that the effect of the peptides on Ulva is mediated via specific peptide-membrane interactions.

National Category
Physical Chemistry
URN: urn:nbn:se:liu:diva-15020OAI: diva2:37625
Available from: 2008-10-09 Created: 2008-10-09 Last updated: 2010-01-14
In thesis
1. Structural and Functional Studies of De Novo Designed Peptides at Surfaces
Open this publication in new window or tab >>Structural and Functional Studies of De Novo Designed Peptides at Surfaces
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The work presented in this thesis deals with the structural and functional properties of peptides at surfaces. The interaction of peptides with surfaces is an ever so common occurrence in our every day life, from the bug squashed on the windshield of our car to the barnacle on our boat, and from the blood plasma used in the hospital to the proteins in our cells. The effect these occurrences has on our lives is diverse, the bug is annoying whereas the barnacle settlement of ship hull is costly for marine transportation, the blood plasma contains components of vital importance for our immunological defense system and the proteins in our cells are crucial for regulatory processes and life.One part of this thesis, performed as a part of the EU-founded project AMBIO, deals with the concept of marine biofouling. A number of short peptides have been designed, synthesized, and used to investigate their effect on the settlement on marine biofoulers, such as the Ulva linza algae and the Navicula diatom, on template surfaces coated with thin layers of these molecules. The surfaces have been thoroughly investigated with respect of their physio-chemical properties before and after submersion in artificial seawater and ultimately in suspensions containing the organisms. The most interesting results were obtained with an arginine-rich peptide coating that when introduced to Ulva linza zoospores, displayed extensive settlement, compared to reference surfaces. In addition, a large fraction of the settled spores had an abnormal morphology.The other part of this thesis is focused on designed peptides that when adsorbed on a negatively charged surface adopts a well-defined secondary structure, either α-helical or β-sheet. Precisely placed amino acids in the peptides will strongly disfavor structure in solution, primarily due to electrostatic repulsion, but when the peptides are adsorbed on the negatively charged surfaces, they adopt a well-defined secondary structure due to ion pair bonding. These interactions have been thoroughly investigated by systematic variations of the side-chains. In order to determine the factors contributing to the induced structure, several peptides with different amino acid sequences have been synthesized. Factors that have been investigated include 1) the positive charge density, 2) distribution of positive charges, 3) negative charge density, 4) increasing hydrophobicity, and 5) incorporating amino acids with different helix propensities. Moreover, pH dependence and the effect of different interaction partners have also been investigated. It has also been shown that the system can be modified to incorporate a catalytic site that is only active when the helix is formed. This research will increase our understanding of peptide-surface interactions and might be of importance for both bionanotechnology and medicine.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2008. 52 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1199
Biofouling, vesicles, nanoparticles, peptide, peptide design, circular dichroism
National Category
Physical Chemistry
urn:nbn:se:liu:diva-15022 (URN)978-91-7393-840-2 (ISBN)
Public defence
2008-09-05, Planck, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Available from: 2008-10-09 Created: 2008-10-09 Last updated: 2009-05-11Bibliographically approved

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Nygren, PatrikEderth, ThomasEkblad, TobiasLiedberg, Bo
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