The Experts below are selected from a list of 45 Experts worldwide ranked by ideXlab platform
Lars Konermann - One of the best experts on this subject based on the ideXlab platform.
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A Long Lifetime Component in the tryptophan fluorescence of some proteins
European Biophysics Journal, 2004Co-Authors: Klaus D??ring, Lars Konermann, Thomas Surrey, Fritz J??hnigAbstract:The tryptophan fluorescence of two membrane proteins (outer membrane protein A and lactose permease), a 21-residue hydrophobic peptide, three soluble proteins (rat serum albumin, ribonuclease T1, and azurin), and N-acetyltryptophanamide (NATA) was investigated by time-resolved measurements extended over 65 ns. A Long Lifetime Component with a characteristic time of 25 ns and an amplitude below 1% was found for outer membrane protein A, lactose permease, the peptide in lipid membranes, and azurin in water, but not for rat serum albumin, ribonuclease T1, and NATA in water. When outer membrane protein A was dissolved and unfolded in guanidinum hydrochloride, the Long Lifetime Component disappeared. Hence, a hydrophobic environment seems to be a necessary requirement for the Long Lifetime Component to be present. However, NATA dissolved in butanol does not exhibit the Long Lifetime Component, while the peptide dissolved in the same solvent under conditions which preserve its helical structure does show the Long Lifetime. Thus, a regular secondary structure for the polypeptide chain to which the tryptophan residue beLongs seems to be a second necessary requirement for the Long Lifetime Component to be present. The Long Lifetime Component may therefore be seen in the context of protein substates.
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The use of a Long-Lifetime Component of tryptophan to detect slow orientational fluctuations of proteins
Biophysical Journal, 1997Co-Authors: Klaus Döring, Lars Konermann, Werner Beck, Fritz JähnigAbstract:The membrane protein porin and a synthetic polypeptide of 21 hydrophobic residues were inserted into detergent micelles or lipid membranes, and the fluorescence of their single tryptophan residue was measured in the time- resolved and polarized mode. In all cases, the tryptophan fluorescence exhibits a Long-Lifetime Component of about 20 ns. This Long-Lifetime Component was exploited to detect slow orientational motions in the range of tens of nanoseconds via the anisotropy decay. For this purpose, the analysis of the anisotropy has to be extended to account for different orientations of the dipoles of the short- and Long-Lifetime Components. This is demonstrated for porin and the polypeptide solubilized in micelles, in which the Longest relaxation time reflects the rotational diffusion of the micelle. When the polypeptide is inserted into lipid membranes, it forms a membrane-spanning α-helix, and the slowest relaxation process is interpreted as reflecting orientational fluctuations of the helix.
Fritz J??hnig - One of the best experts on this subject based on the ideXlab platform.
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A Long Lifetime Component in the tryptophan fluorescence of some proteins
European Biophysics Journal, 2004Co-Authors: Klaus D??ring, Lars Konermann, Thomas Surrey, Fritz J??hnigAbstract:The tryptophan fluorescence of two membrane proteins (outer membrane protein A and lactose permease), a 21-residue hydrophobic peptide, three soluble proteins (rat serum albumin, ribonuclease T1, and azurin), and N-acetyltryptophanamide (NATA) was investigated by time-resolved measurements extended over 65 ns. A Long Lifetime Component with a characteristic time of 25 ns and an amplitude below 1% was found for outer membrane protein A, lactose permease, the peptide in lipid membranes, and azurin in water, but not for rat serum albumin, ribonuclease T1, and NATA in water. When outer membrane protein A was dissolved and unfolded in guanidinum hydrochloride, the Long Lifetime Component disappeared. Hence, a hydrophobic environment seems to be a necessary requirement for the Long Lifetime Component to be present. However, NATA dissolved in butanol does not exhibit the Long Lifetime Component, while the peptide dissolved in the same solvent under conditions which preserve its helical structure does show the Long Lifetime. Thus, a regular secondary structure for the polypeptide chain to which the tryptophan residue beLongs seems to be a second necessary requirement for the Long Lifetime Component to be present. The Long Lifetime Component may therefore be seen in the context of protein substates.
Fritz Jähnig - One of the best experts on this subject based on the ideXlab platform.
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The use of a Long-Lifetime Component of tryptophan to detect slow orientational fluctuations of proteins
Biophysical Journal, 1997Co-Authors: Klaus Döring, Lars Konermann, Werner Beck, Fritz JähnigAbstract:The membrane protein porin and a synthetic polypeptide of 21 hydrophobic residues were inserted into detergent micelles or lipid membranes, and the fluorescence of their single tryptophan residue was measured in the time- resolved and polarized mode. In all cases, the tryptophan fluorescence exhibits a Long-Lifetime Component of about 20 ns. This Long-Lifetime Component was exploited to detect slow orientational motions in the range of tens of nanoseconds via the anisotropy decay. For this purpose, the analysis of the anisotropy has to be extended to account for different orientations of the dipoles of the short- and Long-Lifetime Components. This is demonstrated for porin and the polypeptide solubilized in micelles, in which the Longest relaxation time reflects the rotational diffusion of the micelle. When the polypeptide is inserted into lipid membranes, it forms a membrane-spanning α-helix, and the slowest relaxation process is interpreted as reflecting orientational fluctuations of the helix.
Klaus D??ring - One of the best experts on this subject based on the ideXlab platform.
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A Long Lifetime Component in the tryptophan fluorescence of some proteins
European Biophysics Journal, 2004Co-Authors: Klaus D??ring, Lars Konermann, Thomas Surrey, Fritz J??hnigAbstract:The tryptophan fluorescence of two membrane proteins (outer membrane protein A and lactose permease), a 21-residue hydrophobic peptide, three soluble proteins (rat serum albumin, ribonuclease T1, and azurin), and N-acetyltryptophanamide (NATA) was investigated by time-resolved measurements extended over 65 ns. A Long Lifetime Component with a characteristic time of 25 ns and an amplitude below 1% was found for outer membrane protein A, lactose permease, the peptide in lipid membranes, and azurin in water, but not for rat serum albumin, ribonuclease T1, and NATA in water. When outer membrane protein A was dissolved and unfolded in guanidinum hydrochloride, the Long Lifetime Component disappeared. Hence, a hydrophobic environment seems to be a necessary requirement for the Long Lifetime Component to be present. However, NATA dissolved in butanol does not exhibit the Long Lifetime Component, while the peptide dissolved in the same solvent under conditions which preserve its helical structure does show the Long Lifetime. Thus, a regular secondary structure for the polypeptide chain to which the tryptophan residue beLongs seems to be a second necessary requirement for the Long Lifetime Component to be present. The Long Lifetime Component may therefore be seen in the context of protein substates.
Klaus Döring - One of the best experts on this subject based on the ideXlab platform.
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The use of a Long-Lifetime Component of tryptophan to detect slow orientational fluctuations of proteins
Biophysical Journal, 1997Co-Authors: Klaus Döring, Lars Konermann, Werner Beck, Fritz JähnigAbstract:The membrane protein porin and a synthetic polypeptide of 21 hydrophobic residues were inserted into detergent micelles or lipid membranes, and the fluorescence of their single tryptophan residue was measured in the time- resolved and polarized mode. In all cases, the tryptophan fluorescence exhibits a Long-Lifetime Component of about 20 ns. This Long-Lifetime Component was exploited to detect slow orientational motions in the range of tens of nanoseconds via the anisotropy decay. For this purpose, the analysis of the anisotropy has to be extended to account for different orientations of the dipoles of the short- and Long-Lifetime Components. This is demonstrated for porin and the polypeptide solubilized in micelles, in which the Longest relaxation time reflects the rotational diffusion of the micelle. When the polypeptide is inserted into lipid membranes, it forms a membrane-spanning α-helix, and the slowest relaxation process is interpreted as reflecting orientational fluctuations of the helix.
