An investigation of chlorophyll f-binding to peptide ligands

Min Chena, Miguel Hernandez-Prietoa, Roger Hillerb
aSchool of Life and Environment Sciences, University of Sydney, Austrailia; bDepartment of Biological Sciences, Macquarie University, Australia

Chlorophyll f is a new member in the chlorophyll family [1], which has the most red- shifted absorption Qy peak among chlorophylls isolated from oxygenic photosynthetic organisms. The introduction of the electronegative 2-formyl group in Chl f extends the electronic distribution along the Qy axis, and shifts the absorbance maximum to longer wavelength [2]. In order to understand the properties of chlorophyll f-binding peptide ligands, we performed in vitro reconstitution experiments using either a designed synthetic peptide containing the sequence NH2-GLLAWRSHIVELAAGG- CONH2 [3] or the PCP (Peridinin-Chlorophyll Protein) system [4]. The low affinity between Chl f and the synthetic peptide is observed, which agrees well with the proposed hypothesis that the electronegative character of the 2-formyl group of Chl f has the same effects as the 7-formyl group of Chl b [5]. Therefore, Chl f might require “harder” Lewis bases in protein binding ligands, as that of Chl b or Chl c. However, the interaction between Chl f and purified PCP showed conflicting results. The spectral analysis of Chl f-binding PCP complexes will be discussed.

References

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[2] Y.L, Z-L Cai, M Chen J Phys Chem B, 2013, 117:11309–11317.
[3] M Chen, L Eggink, JK Hoober, A. Larkum J Amer Chem Soc 2005, 127, 2052-2053.
[4] T Schult, RG Hiller, E Hofmann FEBS Lett. 2010, 584:973-978
[5] M Chen Ann. Rev. of Biochem. 2014 83: 317-340