Functional Coupling of Biohybrid Photosynthetic Antennae and Reaction Center Complexes: Quantitative Comparison with Native Antennae

• Published in: The journal of physical chemistry. B 2023-12, Vol.127 (48), p.10315-10325
• Main Authors: Dewa, Takehisa, Kimoto, Komei, Kasagi, Genki, Harada, Hiromi, Sumino, Ayumi, Kondo, Masaharu
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - chemistry; Light-Harvesting Protein Complexes - chemistry; Photosynthesis; Rhodobacter sphaeroides - metabolism
• ISSN: 1520-6106; 1520-5207; 1520-5207
• DOI: 10.1021/acs.jpcb.3c04922

Light-harvesting (LH) complexes in photosynthetic organisms absorb photons within limited wavelength ranges over a broad solar spectrum. Extension of the LH wavelength has been realized by attaching artificial fluorophores to LH complexes (biohybrid LH complexes) for complementing the limited-wavelength regions. However, how efficiently such fluorophores in biohybrid LH complexes function to drive the photocatalytic reaction center (RC) has not been quantitatively evaluated, specifically in comparison with native LH antenna complexes. In this study, we prepared various biohybrid LH1-RC complexes (from ), to quantitatively evaluate the LH activity of the attached external chromophores through a photocurrent generation reaction by LH1-RC on an electrode. For a direct comparison of the LH activity among the LH chromophores that were examined, we introduced the term, which represents the extent of the functional coupling of LH and the photochemical reactions in the RC. We determined that the hydrophobic fluorophore ATTO647N attached to LH1 possesses the highest LH activity among the examined hydrophilic fluorophores such as Alexa647, and its activity is comparable to that of native LH1(-RC). The LH activity of LH2 (from strain 10050) and its biohybrid LH2s were examined for the comprehensive assessment of their LH activity.