title: Application of peptide gemini surfactants as novel solubilization surfactants for photosystems I and II of cyanobacteria.
abstract: We designed novel peptide gemini surfactants (PG-surfactants), DKDKC12K and DKDKC12D, which can solubilize Photosystem I (PSI) of Thermosynecoccus elongatus and Photosystem II (PSII) of Thermosynecoccus vulcanus in an aqueous buffer solution. To assess the detailed effects of PG-surfactants on the original supramolecular membrane protein complexes and functions of PSI and PSII, we applied the surfactant exchange method to the isolated PSI and PSII. Spectroscopic properties, light-induced electron transfer activity, and dynamic light scattering measurements showed that PSI and PSII could be solubilized not only with retention of the original supramolecular protein complexes and functions but also without forming aggregates. Furthermore, measurement of the lifetime of light-induced charge-separation state in PSI revealed that both surfactants, especially DKDKC12D, displayed slight improvement against thermal denaturation below 60 °C compared with that using β-DDM. This degree of improvement in thermal resistance still seems low, implying that the peptide moieties did not interact directly with membrane protein surfaces. By conjugating an electron mediator such as methyl viologen (MV(2+)) to DKDKC12K (denoted MV-DKDKC12K), we obtained derivatives that can trap the generated reductive electrons from the light-irradiated PSI. After immobilization onto an indium tin oxide electrode, a cathodic photocurrent from the electrode to the PSI/MV-DKDKC12K conjugate was observed in response to the interval of light irradiation. These findings indicate that the PG-surfactants DKDKC12K and DKDKC12D provide not only a new class of solubilization surfactants but also insights into designing other derivatives that confer new functions on PSI and PSII.
authors: Graduate School of Engineering, Nagoya Institute of Technology , Gokiso-cho, Showa-ku, Nagoya, Aichi 466-8555, Japan.
authors: Shuhei
authors: S
authors: Koeda
authors: Katsunari
authors: K
authors: Umezaki
authors: Tomoyasu
authors: T
authors: Noji
authors: Atsushi
authors: A
authors: Ikeda
authors: Keisuke
authors: K
authors: Kawakami
authors: Masaharu
authors: M
authors: Kondo
authors: Yasushi
authors: Y
authors: Yamamoto
authors: Jian-Ren
authors: JR
authors: Shen
authors: Keijiro
authors: K
authors: Taga
authors: Takehisa
authors: T
authors: Dewa
authors: Shigeru
authors: S
authors: Ito
authors: Mamoru
authors: M
authors: Nango
authors: Toshiki
authors: T
authors: Tanaka
authors: Toshihisa
authors: T
authors: Mizuno
mesh_terms: D000458:Cyanobacteria / Q000737:chemistry* / Q000378:metabolism; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry*; D045331:Photosystem I Protein Complex / Q000737:chemistry* / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000378:metabolism; D012995:Solubility; D013501:Surface-Active Agents / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D010455:Peptides; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D013501:Surface-Active Agents