@phdthesis{Lengefeld2010,
  author    = {Lengefeld, Jan},
  title     = {Zirkulardichroismus-Messungen mit Synchrotronstrahlung am BESSY : M{\"o}glichkeiten und Grenzen bei der Untersuchung biologischer Proben},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-44263},
  school      = {Universit{\"a}t Potsdam},
  year      = {2010},
  abstract  = {In dieser Arbeit wurden die M{\"o}glichkeiten und Grenzen f{\"u}r Zirkulardichroismus-Messungen mit Synchrotronstrahlung untersucht. Dazu wurde ein Messaufbau f{\"u}r Zirkulardichroismus-Messungen an zwei Strahlrohren am Berliner Elektronenspeicherring f{\"u}r Synchrotronstrahlung eingesetzt, die f{\"u}r Messungen im Bereich des ultravioletten Lichts geeignet sind. Eigenschaften der Strahlrohre und des Messaufbau wurden in einigen wichtigen Punkten mit kommerziellen Zirkulardichroismus-Spektrometern verglichen. Der Schwerpunkt lag auf der Ausdehnung des zug{\"a}nglichen Wellenl{\"a}ngenbereichs unterhalb von 180 nm zur Untersuchung des Zirkulardichroismus von Proteinen in diesem Bereich. In diesem Bereich ist es nicht nur die Lichtquelle sondern vor allem die Absorption des Lichts durch Wasser, die den Messbereich bei der Messung biologischer Proben in w{\"a}ssriger L{\"o}sung einschr{\"a}nkt. Es wurden Bedingungen gefunden, unter denen der Messbereich auf etwa 160 nm, in einigen F{\"a}llen bis auf 130 nm ausgedehnt werden konnte. Dazu musste die Pfadl{\"a}nge deutlich reduziert werden und verschieden Probenk{\"u}vetten wurden getestet. Der Einfluss der dabei auftretenden Spannungsdoppelbrechung in den Probenk{\"u}vetten auf das Messsignal konnte mit einem alternativen Messaufbau deutlich reduziert werden. Systematische Fehler im Messsignal und auftretende Strahlensch{\"a}den begrenzen jedoch die Zuverl{\"a}ssigkeit der gemessenen Spektren. Bei Proteinfilmen schr{\"a}nkt die Absorption von Wasser den Messbereich kaum ein. Es wurden jedoch meist deutliche Unterschiede zwischen den Spektren von Proteinfilmen und den Spektren von Proteinen in w{\"a}ssriger L{\"o}sung festgestellt. Solange diese Unterschiede nicht minimiert werden k{\"o}nnen, stellen Proteinfilme keine praktikable Alternative zu Messungen in w{\"a}ssriger L{\"o}sung dar.},
  language  = {de}
}
@article{HoffmannKaneNettelsetal.2007,
  author    = {Hoffmann, Armin S. and Kane, Avinash S. and Nettels, Daniel and Hertzog, David E. and Baumg{\"a}rtel, Peter and Lengefeld, Jan and Reichardt, Gerd and Horsley, David A. and Seckler, Robert and Bakajin, Olgica and Schuler, Benjamin},
  title     = {Mapping protein collapse with single molecule fluorescence and kinetic synchrotron radiation circular dichroism spectroscopy},
  issn      = {0027-8424},
  year      = {2007},
  language  = {en}
}
@article{HundertmarkDimovaLengefeldetal.2011,
  author    = {Hundertmark, Michaela and Dimova, Rumiana and Lengefeld, Jan and Seckler, Robert and Hincha, Dirk K.},
  title     = {The intrinsically disordered late embryogenesis abundant protein LEA18 from Arabidopsis thaliana modulates membrane stability through binding and folding.},
  issn      = {0006-3002},
  year      = {2011},
  abstract  = {Intrinsically disordered proteins (IDPs) constitute a substantial part of cellular proteomes. Late embryogenesis abundant (LEA) proteins are mostly predicted to be IDPs associated with dehydration tolerance in many plant, animal and bacterial species. Their functions, however, are largely unexplored and also their structure and interactions with potential target molecules have only recently been experimentally investigated in a small number of proteins. Here, we report on the structure and interactions with membranes of the Pfam LEA_1 protein LEA18 from the higher plant Arabidopsis thaliana. This functionally uncharacterized positively charged protein specifically aggregated and destabilized negatively charged liposomes. Isothermal titration calorimetry showed binding of the protein to both charged and uncharged membranes. LEA18 alone was largely unstructured in solution. While uncharged membranes had no influence on the secondary structure of LEA18, the protein partially folded into ;-sheet structure in the presence of negatively charged liposomes. These data suggest that LEA18 does not function as a membrane stabilizing protein, as suggested for other LEA proteins. Instead, a possible function of LEA18 could be the composition-dependent modulation of membrane stability, e.g., during signaling or vesicle-mediated transport. Research Highlights},
  language  = {en}
}
@article{HundertmarkDimovaLengefeldetal.2011,
  author    = {Hundertmark, Michaela and Dimova, Rumiana and Lengefeld, Jan and Seckler, Robert and Hincha, Dirk K.},
  title     = {The intrinsically disordered late embryogenesis abundant protein LEA18 from Arabidopsis thaliana modulates membrane stability through binding and folding},
  series = {Biochimica et biophysica acta : Biomembranes},
  volume    = {1808},
  journal   = {Biochimica et biophysica acta : Biomembranes},
  number    = {1},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0005-2736},
  doi       = {10.1016/j.bbamem.2010.09.010},
  pages     = {446 -- 453},
  year      = {2011},
  abstract  = {Intrinsically disordered proteins (IDPs) constitute a substantial part of cellular proteomes. late embryogenesis abundant (LEA) proteins are mostly predicted to be IDPs associated with dehydration tolerance in many plant, animal and bacterial species. Their functions, however, are largely unexplored and also their structure and interactions with potential target molecules have only recently been experimentally investigated in a small number of proteins. Here, we report on the structure and interactions with membranes of the Pfam LEA_1 protein LEA18 from the higher plant Arabidopsis thaliana. This functionally uncharacterized positively charged protein specifically aggregated and destabilized negatively charged liposomes. Isothermal titration calorimetry showed binding of the protein to both charged and uncharged membranes. LEA18 alone was largely unstructured in solution. While uncharged membranes had no influence on the secondary structure of LEA18, the protein partially folded into beta-sheet structure in the presence of negatively charged liposomes. These data suggest that LEA18 does not function as a membrane stabilizing protein, as suggested for other LEA proteins. Instead, a possible function of LEA18 could be the composition-dependent modulation of membrane stability, e.g., during signaling or vesicle-mediated transport.},
  language  = {en}
}