Fig. 3.

Cross-linking of LH2 complexes. (A) Structures and reactions of the two cross-linking agents used (DSP and EGS). (B) αβ-heterodimers observed after DSP cross-linking of a low light adapting sample containing 5 different polypeptides (α1, α2, β1, β2, and β3). The numbered peaks 0–6 correspond to masses (see text and Table S2). (C) αα- and ββ-homodimers observed after EGS cross-linking of a sample containing three different polypeptides (α1, β1, and β2). The peaks are numbered 0–7 and in each case the pairs, labeled a and b, differ by the mass of one cross-link (Table S2).