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Photosynthetic organisms produce ATP and NADPH using light as an energy source and further utilize these cofactors during metabolism. Photosynthesis involves linear and cyclic electron flows; as the cyclic electron flow produces ATP more effectively than the linear electron flow without NADPH, the cell efficiently adjusts ATP and NADPH production using the two different pathways. Nevertheless, direct measurement of ATP and NADPH production during photosynthesis has been difficult. In the present study, the photosynthetic ATP and NADPH production rates of Synechocystis sp. PCC 6803 under three different single peak wavelength lights (blue: 470 nm, R630: 630 nm, and R680: 680 nm) were evaluated based on 13C-metabolic flux analysis (13C-MFA) by considering the mass balance of ATP and NADPH between photosynthesis and metabolism. The ratios of ATP/NADPH production via photosynthesis were estimated as 3.13, 1.70, and 2.10 under blue, R630, and R680 light conditions, respectively. Moreover, the linear and cyclic electron flow ratios were estimated to be 1.1–2.2, 0.2–0.5, and 0.5–1.0 under blue, R630, and R680 light conditions, respectively. The predicted linear and cyclic electron flow ratios were consistent with the excitation ratio between photosystems I and II, as observed in the steady-state fluorescence spectra.

Upon combining chiral peptides (the most basic chiral source) with pyrene moieties, we found that chiral oligopeptides bearing two-pendant pyrenyl units exhibited circularly polarised luminescence (CPL) originating from intramolecular excimers at 450-490 nm in various solvents, and the sign of their CPL signals depended on the type of solvent employed. The CPL and circular dichroism signs and intensities could be tuned by the introduction of a piperidine unit into the chiral peptide chain; thus, the obtained structure could be considered a practical Lock ON-OFF system for oligopeptide luminophores.

The photoexcited and ground state chiralities of enantiopure oligopeptides bearing two pyrenyl groups (DD-2/LL-2: four methylene spacer between two pyrenyl groups and DD-1/LL-1: no methylene spacer thereof) in eight common organic solvents (CHCl3, CH2Cl2, MeOH, CH3CN, DMF, NMP, DMAc, and acetone) were investigated by means of circularly polarized luminescence (CPL) and circular dichroism (CD) spectroscopies. It was found that chiroptical signs of pyrene-origin CPL and CD signals largely depend on the nature of solvents and are susceptible to the methylene spacer. Actually, the excimer-origin CPL signs at 450–510 nm of DD-1/LL-1 in DMF were (–)/(+), respectively, while those in other solvents were oppositely (+)/(–), respectively. On the other hand, in DD-2/LL-2, the excimer-origin CPL signs were (–)/(+) in CH2Cl2 (and CHCl3), respectively, and (+)/(–) in MeOH/DMF/NMP/DMAc, respectively. The solvent dependent and the methylene spacer dependent CD sign inversion of DD-1/LL-1 and DD-2/LL-2 were also found. These results led to conclude that the solvent molecule and the methylene spacer collaboratively affect both the ground state chirality and the photoexcited chirality.

An engineering tool for controlling flux distribution on metabolic pathways to an appropriate state is highly desirable in bioproduction. An optogenetic switch, which regulates gene expression by light illumination is an attractive on/off switchable system, and is a promising way for flux control with an external stimulus. We demonstrated a light-inducible flux control between glycolysis and the methylglyoxal (MGO) pathway in Escherichia coli using a CcaS/CcaR system. CcaR is phosphorylated by green light and is dephosphorylated by red light. Phosphorylated CcaR induces gene expression under the cpcG2 promoter. The tpiA gene was expressed under the cpcG2 promoter in a genomic tpiA deletion strain. The strain was then cultured with glucose minimum medium under green or red light. We found that tpiA messenger RNA level under green light was four times higher than that under red light. The repression of tpiA expression led to a decrease in glycolytic flux, resulting in slower growth under red light (0.25 hr -1 ) when compared to green light (0.37 hr -1 ). The maximum extracellular MGO concentration under red light (0.2 mM) was higher than that under green light (0.05 mM). These phenotypes confirm that the MGO pathway flux was enhanced under red light.

We prepared 16 novel chiral peptide–pyrene organic luminophores with different distances between the fluorescent pyrene groups and investigated their properties in CHCl3 at room temperature. The peptide–pyrene organic luminophores bearing two pyrene groups emit strong excimer circularly polarized luminescence (CPL) in the solution state. Two pendant pyrenyl groups in a series of chiral oligopeptides clearly revealed excimer CPL in chloroform at 480–490 nm (|gem| ≈ (2–8) × 10–3). When the distance between the two pyrenes increased, the sign of the CPL signals was inverted twice, while the sign of the corresponding circular dichroism (CD) signals was retained, (|gCD| ≈ (3–8) × 10–5).

The coordination of Eu(iii) (from Eu(iii)(hfa)3) by chiral P(iii) (from BINAP) led to circularly polarised luminescence in dilute solutions on the order of |gem| ≈ 10−2 at 5D0 → F1 and |gem| ≈ 10−2 at 5D0 → F2 transitions, i.e., in chloroform and acetone.

The circularly polarised luminescence and circular dichroism signs of the blue circularly polarised luminescence generated by two photoexcited pyrenes as puppets are controlled by the wire structure of the C2-symmetric binaphthyl as puppeteer. The experimental results, though at variance with theoretical simulation, offer a rational design in the photoexcited and ground state chiralities of luminophores.