Assembly of a mixture of isomeric BChl c from Chlorobium limicola as determined by intermolecular 13C-13C dipolar correlations: coexistence of dimer-based and pseudo-monomer-based stackings
| Autor: | Kengo Akiba, Yoshinori Kakitani, Yasushi Koyama, Ayako Egawa, Tadashi Mizoguchi, Hideo Akutsu, Hiroyoshi Nagae, Toshimichi Fujiwara |
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| Rok vydání: | 2006 |
| Předmět: |
Models
Molecular Carbon Isotopes Chemistry Dimer Intermolecular force Carbon-13 NMR Chlorobium In Vitro Techniques Biochemistry Spectral line Dilution Crystallography chemistry.chemical_compound Dipole Monomer Bacterial Proteins Isomerism Models Chemical Bacteriochlorophyll Bacteriochlorophylls Dimerization Nuclear Magnetic Resonance Biomolecular |
| Zdroj: | Biochemistry. 45(24) |
| ISSN: | 0006-2960 |
| Popis: | A mixture of bacteriochlorophyll (BChl) c isomers was extracted from the cells of Chlorobium limicola that were grown in the media of 13C-enriched and natural-abundance isotopic compositions. The magic-angle spinning 13C NMR proton-driven spin-diffusion spectra were recorded with mixing times of 50, 100, and 250 ms for two different kinds of in vitro aggregates, one consisting of pure [13C]BChl c and the other consisting of a 1:1 mixture of [13C]BChl c and [12C]BChl c; those peaks whose intensities were reduced to approximately 1/4 by this dilution were assigned to intermolecular 13C-13C dipolar correlation peaks. On the other hand, the nearest-neighbor intermolecular carbon-carbon close contacts with distances of 4-6 A were simulated, to predict observed correlation peaks, for six different models of BChl c assembly. They include weakly overlapped monomers forming structure 1 and structure 2, strongly overlapped dimers forming straight and inclined columns, and weakly overlapped dimers forming aligned and displaced layers. Comparison between the observed correlation peaks and the predicted carbon-carbon close contacts, for both the macrocycles and the side chains, led us to a conclusion that the weakly overlapped dimers forming displaced layers are most likely the assembly of the BChl c molecules in the aggregate. |
| Databáze: | OpenAIRE |
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