HIGH-RESOLUTION ATOMIC FORCE MICROSCOPY OF NATIVE MEMBRANES - Life at the Nanoscale: Atomic Force Microscopy of Live Cells - page 29

core-LH2 and so on. Additional LH2 synthetized under low-light conditions
segregate in antenna domains. The photosynthetic apparatus structure of
Phsp. Rsp. photometricum. 44 LH complexes

are segregated into two structurally different types of domains, consisting of
a mixture of core and octameric LH2 complexes, as well as paracrystalline,
hexagonally packed octameric LH2 rings. One speciic example is the
photosynthetic membrane of

molischianum resembles that of

which has no LH2 complexes and
shows core complexes forming a hexagonal lattice in the photosynthetic
membrane. 24
Photosynthetic membranes are densely packed with photosynthetic
proteins favourable for excitation energy transfer; however, such a dense
packing becomes an obstacle for eficient quinone/quinol membrane diffusion
between cores and cyt

Rps. viridis

bc 1 complex. Pair correlation function analysis of the
entire photosynthetic membrane showed that core complexes inluence
their molecular environment within a critical radius of 250 Å. 21 Analysis of
the molecular environment further indicated that the local environment of
core complexes contained more lipid spaces within the membrane, due to the
geometric mismatch between cores and LH2. Short-range core interaction
and larger lipid space inally establish long-range quinone/quinol pathways
through the entire photosynthetic membranes ( Fig. 2.5b ) .

21

(a) (b)

(c)

Figure 2.5. (a) AFM topograph of the native photosynthetic membranes of Rsp.
photometricum , showing the speciic assembly of LH2 and core complexes (Inset:

structural model of native protein assembly). 52 (b) AFM delection image of entire native
chromatophores of Rsp. photometricum and (c) calculated quinone pathways. 21