Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 358472
Title A refined model of the chlorosomal antennae of the green bacterium chlorobium tepidum from proton chemical shift constraints obtained with high-field 2-D and 3-D MAS NMR dipolar correlation spectroscopy
Author(s) Rossum, B.E.J. van; Steengaard, D.B.; Boender, G.J.; Schaffner, K.; Holzwarth, A.R.; Groot, H.J.M. de
Source Biochemistry 40 (2001). - ISSN 0006-2960 - p. 1587 - 1595.
Department(s) ASG Infectieziekten
Publication type Refereed Article in a scientific journal
Publication year 2001
Keyword(s) energy-transfer processes - bacteriochlorophyll-c - chloroflexus-aurantiacus - photosynthetic bacteria - cross-polarization - rotating solids - sulfur bacteria - spectral forms - spinning nmr - c-13 nmr
Abstract Heteronuclear 2-D and 3-D magic-angle spinning NMR dipolar correlation spectroscopy was applied to determine solid-state 1H shifts for aggregated bacteriochlorophyll c (BChl c) in uniformly 13C-enriched light harvesting chlorosomes of the green photosynthetic bacterium Chlorobium tepidum. A complete assignment of 29 different observable resonances of the 61 protons of the aggregated BChl c in the intact chlorosomes is obtained. Aggregation shifts relative to monomeric BChl c in solution are detected for protons attached to rings I, II, and III/V and to their side chains. The 21-H3, 32-H3, and 31-H resonances are shifted upfield by -2.2, -1, and -3.3 ppm, respectively, relative to monomeric BChl c in solution. Although the resonances are inhomogeneously broadened and reveal considerable global structural heterogeneity, the 5-CH and the 7-Me responses are doubled, which provides evidence for the existence of at least two relatively well-defined structurally different arrangements. Ab initio quantum chemical modeling studies were performed to refine a model for the self-assembled BChl c with two different types of BChl stacks. The BChl in the stacks can adopt either anti- or syn-configuration of the coordinative bond, where anti and syn designate the relative orientation of the Mg-OH bond relative to the direction of the 17-171 bond. The analogy between aggregation shifts for BChl c in the chlorosome and for self-assembled chlorophyll a/H2O is explored, and a bilayer model for the tubular supra-structure of sheets of BChl c is proposed, from a homology modeling approach.
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