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Structural and Functional Studies of De Novo Designed Peptides at Surfaces
Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
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.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1199
Keyword [en]
Biofouling, vesicles, nanoparticles, peptide, peptide design, circular dichroism
National Category
Physical Chemistry
Identifiers
URN: urn:nbn:se:liu:diva-15022ISBN: 978-91-7393-840-2 (print)OAI: oai:DiVA.org:liu-15022DiVA: diva2:37627
Public defence
2008-09-05, Planck, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2008-10-09 Created: 2008-10-09 Last updated: 2017-01-11Bibliographically approved
List of papers
1. Induction of structure and function in a designed peptide upon adsorption on a silica nanoparticle
Open this publication in new window or tab >>Induction of structure and function in a designed peptide upon adsorption on a silica nanoparticle
2006 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 45, no 48, 8169-8173 p.Article in journal (Refereed) Published
Abstract [en]

No abstrack available.

Keyword
Amino acids, catalysis, helical structures, nanoparticles, peptides
National Category
Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-14548 (URN)10.1002/anie.200600965 (DOI)
Available from: 2008-02-25 Created: 2008-02-25 Last updated: 2017-12-13Bibliographically approved
2. Fundamental Design Principles That Guide Induction of Helix upon Formation of Stable Peptide−Nanoparticle Complexes
Open this publication in new window or tab >>Fundamental Design Principles That Guide Induction of Helix upon Formation of Stable Peptide−Nanoparticle Complexes
2008 (English)In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 8, no 7, 1844-1852 p.Article in journal (Refereed) Published
Abstract [en]

We have shown that it is possible to design a peptide that has a very low helical content when free in solution but that adopts a well-defined helix when interacting with silica nanoparticles. From a systematic variation of the amino acid composition and distribution in designed peptides, it has been shown that the ability to form helical structure upon binding to the silica surface is dominated by two factors. First, the helical content is strongly correlated with the net positive charge on the side of the helix that interacts with the silica, and arginine residues are strongly favored over lysine residues in these positions. The second important factor is to have a high net negative charge on the side of the helix that faces the solution. Apparently, both attractive and repulsive electrostatic forces dominate the induction and stabilization of a bound helix. It is also evident that using amino acids that have high propensity to form helix in solution are also advantageous for the formation of helix on surfaces.

National Category
Other Basic Medicine
Identifiers
urn:nbn:se:liu:diva-15015 (URN)10.1021/nl080386s (DOI)
Available from: 2008-10-09 Created: 2008-10-09 Last updated: 2017-12-11Bibliographically approved
3. Secondary Structure in de Novo Designed Peptides Induced by Electrostatic Interaction with a Lipid Bilayer Membrane
Open this publication in new window or tab >>Secondary Structure in de Novo Designed Peptides Induced by Electrostatic Interaction with a Lipid Bilayer Membrane
Show others...
2010 (English)In: LANGMUIR, ISSN 0743-7463, Vol. 26, no 9, 6437-6448 p.Article in journal (Refereed) Published
Abstract [en]

We show that it is possible to induce a defined secondary structure in de nova designed peptides upon electrostatic attachment to negatively charged lipid bilayer vesicles without partitioning of the peptides into the membrane, and that the secondary structure can be varied via small changes in the primary amino acid sequence of the peptides. The peptides have a random-coil conformation in solution, and results from far-UV circular dichroism spectroscopy demonstrate that the structure induced by the interaction with silica nanoparticles is solely alpha-helical and also strongly pH-dependent. The present study shows that negatively charged vesicles, to which the peptides are electrostatically adsorbed via cationic amino acid residues, induce either alpha-helices or beta-sheets and that the conformation is dependent on both lipid composition and variations in peptide primary structure. The pH-dependence of the vesicle-induced peptide secondary structure is weak, which correlates well with small differences in the vesicles electrophoretic mobility, and thus the surface charge, as the pH is varied.

Place, publisher, year, edition, pages
ACS American Chemical Society, 2010
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-56297 (URN)10.1021/la100027n (DOI)000276969700056 ()
Note

The previous status of this article was Manuscript.

Available from: 2010-05-07 Created: 2010-05-07 Last updated: 2017-01-11
4. Anomalous settlement behavior of Ulva linza zoospores on cationic oligopeptide surfaces
Open this publication in new window or tab >>Anomalous settlement behavior of Ulva linza zoospores on cationic oligopeptide surfaces
Show others...
2008 (English)In: Biofouling (Print), ISSN 0892-7014, E-ISSN 1029-2454, Vol. 24, no 4, 303-312 p.Article in journal (Refereed) Published
Abstract [en]

Identification of settlement cues for marine fouling organisms opens up new strategies and methods for biofouling prevention, and enables the development of more effective antifouling materials. To this end, the settlement behaviour of zoospores of the green alga Ulva linza onto cationic oligopeptide self-assembled monolayers (SAMs) has been investigated. The spores interact strongly with lysine- and arginine-rich SAMs, and their settlement appears to be stimulated by these surfaces. Of particular interest is an arginine-rich oligopeptide, which is effective in attracting spores to the surface, but in a way which leaves a large fraction of the settled spores attached to the surface in an anomalous fashion. These 'pseudo-settled' spores are relatively easily detached from the surface and do not undergo the full range of cellular responses associated with normal commitment to settlement. This is a hitherto undocumented mode of settlement, and surface dilution of the arginine-rich peptide with a neutral triglycine peptide demonstrates that both normal and anomalous settlement is proportional to the surface density of the arginine-rich peptide. The settlement experiments are complemented with physical studies of the oligopeptide SAMs, before and after extended immersion in artificial seawater, using infrared spectroscopy, null ellipsometry and contact angle measurements.

Keyword
Fouling, algae, self-assembled monolayers, cationic peptides, Ulva, spore
National Category
Physical Chemistry
Identifiers
urn:nbn:se:liu:diva-15018 (URN)10.1080/08927010802192650 (DOI)
Available from: 2008-10-09 Created: 2008-10-09 Last updated: 2017-12-11
5. Interactions of Zoospores of Ulva linza with Arginine-Rich Oligopeptide Monolayers
Open this publication in new window or tab >>Interactions of Zoospores of Ulva linza with Arginine-Rich Oligopeptide Monolayers
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2009 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 25, no 16, 9375-9383 p.Article in journal (Refereed) Published
Abstract [en]

We recently reported oil the strong interactions of zoospores of the green alga, Ulva linza with all arginine-rich oligopeptide self-assembled monolayer (SAM) [Biofouling 2008, 24, 303-312], where the arginine-rich peptide induced not only high spore settlement, but also a form of abnormal settlement, or "pseudo-settlement", whereby it proportion of spores do not go through the normal process of surface exploration, adhesive exocytosis, and loss of flagella. Further. it was demonstrated that both the total number of settled spores and the fraction of pseudosettled spores were related to the surface density of the arginine-rich peptide. Here we present a further investigation of the interactions of zoospores of ulva with a set of oligomeric, de nom 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 measurement. Results confirm the importance of arginine residues for the anomalous pseudosettlement, and we found that settlement is modulated by variations in both the total length and 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" zoospores of Ulva(which present it lipoprotein membrane to the exterior without a discrete polysaccharide cell wall), with the settlement of diatoms (unicellular algae that are surrounded by it silica cell wall), onto the peptide SAMs. Cationic SAMs do not notably affect settlement (attachment), adhesion strength, or viability of diatom cells, Suggesting that the effect of the peptides on zoospores of Ulva is mediated via specific peptide-membrane interactions.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2009
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-19996 (URN)10.1021/la900688g (DOI)
Note

The previous status of this article was Manuscript.

Available from: 2009-08-24 Created: 2009-08-24 Last updated: 2017-12-13Bibliographically approved

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