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W Junge

Publications and source records attributed to W Junge.

142 records · Page 8Linked to original sources
PubMedDate not supplied

The field of possible structures for the chlorophyll a dimer in photosystem I of green plants delineated by polarized photochemistry.

Photoselection experiments with immobilized photosystem I particles have been done to determine the mutual orientation of pigments in the reaction centre. When these particles are excited and interrogated with linearly polarized light, the flash-induced transient absorption changes (mainly from the chlorophyll a dimer) reveal linear dichroism, which yields information on the mutual orientation between the excited and the interrogated transition moments. The interpretation of the data, however, is ambiguous, (1) for reasons of principles inherent in the photoselection technique when applied to complex systems and (2) because of incomplete knowledge about the relative contribution of x- and of y-polarized transitions of chlorophyll a to absorption or to absorption changes at a given wavelength. We find it impossible to attribute any particular structure to the photooxidizable dimer based on photoselection data alone. Instead we present a field of possible structures, imposing constraints on proposed models for the dimer structure.

Chlorophyll↗
PubMedDate not supplied

Subunit delta of chloroplast F0F1-ATPase and OSCP of mitochondrial F0F1-ATPase: a comparison by CD-spectroscopy.

CD spectra have been recorded with subunit delta from chloroplast CF0CF1 and with OSCP from mitochondrial MF0MF1. These subunits are supposed to act similarly at the interface between proton transport through the F0-portion and ATP-synthesis in the F1-portion of their respective F0F1-ATPase. Evaluation of the data for both proteins revealed a very high alpha-helix content of approximately 85% and practically no beta-sheets. Despite their low homology on the primary structure level (23% identity) and their different electrostatic properties (pI-values differ by 3 units), spinach delta and porcine OSCP are indistinguishable with respect to their secondary structure as measured by CD. Prediction and analysis of consensual alpha-helices even in poorly conserved regions indicate a high degree of structural similarity between chloroplast delta and OSCP. In view of the topology and function of delta and OSCP in intact F0F1 these findings are interpreted to indicate the dominance of secondary and tertiary structure over the primary structure in their supposed function between proton flow and ATP-synthesis.

Adenosine Triphosphatases↗