Macrocycle ring deformation as the secondary design principle for light-harvesting complexes

Research output: Contribution to journalArticle


Natural light-harvesting is performed by pigment–protein complexes, which collect and funnel the solar energy at the start of photosynthesis. The identity and arrangement of pigments largely define the absorption spectrum of the antenna complex, which is further regulated by a palette of structural factors. Small alterations are induced by pigment–protein interactions. In light-harvesting systems 2 and 3 from Rhodoblastus acidophilus, the pigments are arranged identically, yet the former has an absorption peak at 850 nm that is blue-shifted to 820 nm in the latter. While the shift has previously been attributed to the removal of hydrogen bonds, which brings changes in the acetyl moiety of the bacteriochlorophyll, recent work has shown that other mechanisms are also present. Using computational and modeling tools on the corresponding crystal structures, we reach a different conclusion: The most critical factor for the shift is the curvature of the macrocycle ring. The bending of the planar part of the pigment is identified as the second-most important design principle for the function of pigment–protein complexes—a finding that can inspire the design of novel artificial systems.


  • Luca De Vico
  • André Anda
  • Vladimir Al Osipov
  • Anders Madsen
  • Thorsten Hansen
External organisations
  • University of Siena
  • University of Copenhagen
  • RMIT University
  • University of California, Irvine
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Biochemistry and Molecular Biology
  • Physical Chemistry


  • Bacteriochlorophyll, Chromophore mimics, LH3, Macrocycle ring deformation, MS-RASPT2
Original languageEnglish
Pages (from-to)E9051-E9057
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number39
Publication statusPublished - 2018 Sep 25
Publication categoryResearch