Reversible chemical cross‐linking of the light‐harvesting polypeptides of Rhodopseudomonas viridis

Abstract

The topography of the light‐harvesting polypeptides of Rhodopseudomonas viridis was investigated using cleavable chemical cross‐linkers. To this end a set of succinimidyl esters and surface‐specific sulfosuccinimidyl esters of different span widths were synthesized. The corss‐linking reagents have been characterized using NMR and infrared spectroscopy and thin‐layer chromatography. The cross‐linking reaction was carried out under physiolocigal conditions and the aggregates were analyzed by the methods of one‐ and two‐dimensional polyacrylamide gel electrophoresis and by immunoblot analysis. We found cross‐linkage between B1015‐α and B1015‐α, between B1015‐α and B1015‐β and B1015‐β. Aggregates of higher molecular mass were hetero‐oligomers of B1015‐α and B1015‐β contaning three and four polypeptides, respectively. The results obtained in this work indicate a very tight contact among the light‐harvesting polypeptides. We assume that the light‐harvesting polypeptides are localized alternately as dimers of B1015‐α and B1015‐β around the reaction centre core. Copyright © 1985, Wiley Blackwell. All rights reserved