The technical challenges, research difficulties and progress of solar energy conversion to chemical energy.

On November 5, the journal Nature Chemistry published a research article by Wang Jiangyun of the Institute of Biophysics of the Chinese Academy of Sciences entitled A Genetically encoded dydd d'Efeensitizer protein sleaper s the design of a photocataco2 snob.
the paper, a photosensitive protein designed by the group that can be genetically coded, successfully simulates the function of natural photosynthesis system siphoning light energy and catalyzing carbon dioxide reduction.
In recent years, how to convert solar energy into chemical energy has become a key issue in the field of chemical and biological research.
plant photosynthesis system as a natural solution, because of its clean, self-assembled, sustainable and efficient photoelectric separation efficiency and other advantages are widely concerned.
at present, how to use and simulate the high photosynthesis efficiency of photosynthesis to drive challenging chemical transformation is a hot topic.
the technical challenges and research difficulties affecting the development of this field are: 1, natural photosynthesis system consists of complex membrane protein sub-bases and a variety of coenzymes, which brings inconvenience to research and practical application; In order to solve these problems
, Wang Jiangyun's team has been working for many years to apply synthetic biology methods and develop artificial photosynthesis systems for gene coding, which combine the advantages of natural photosystems and chemical small molecular catalysts.
this artificially designed photosynthesis protein can not only provide new ideas for the study of challenging chemical transformation, but also provide a research basis for the evolution of artificial organisms with non-natural photocatalytic activity.
previous research by the team, only about 27kD of fluorescent proteins have the potential to transform into photosynthesis proteins similar to natural light systems.
first, it was found that fluorescent proteins are excited by light, and their hair masses can produce species with high reduction activity, an intermediate that efficiently transmits electrons to electron receptors located outside the protein beta folding bucket.
on the other hand, using gene crypt expansion technology, non-natural amino acids can be specifically inserted to replace the tyrosine, which forms the original hair color group.
this allows researchers to rationally design the chemical structure of fluorescent color groups of fluorescent proteins, optimizing their absorption spectrum, excitation state life, free radical reduction potential and a range of other photochemical properties (Angew. Chem. Intl. Ed. 2012, 51, 10261-5; angew. Chem. Intl. Ed. 2013, 52, 4805-9; J. Am. Chem. Soc. 2014, 136 , 13094-7; J. Am. Chem. Soc., 2015, 137,7270-3). The core problem of
designing an efficient CO2 photoreducing protein based on fluorescent protein mutants is how to extend the life of the reductive intermediate state generated by the excitation of its hair group and reduce its reduced potential.
in this article, the team chose a tyrosine analogue (BpA) with dibenzone instead of the base to modify the hair group.
benzoyl ketone is a photosensitive agent commonly used in organic photocatalytic.
when it is exposed to light at a certain wavelength, its excitation state crosses the long-lived triple state with nearly 100% efficiency.
this triple state and sacrifice the reducing agent reaction to produce a highly active free radical state, catalyzing downstream redox reaction.
newly generated photosensitive protein (PSP) retains this characteristic after inserting BPa-based fluorescent protein hair color clumps into the cryptographic sub-expansion method.
transient absorption spectroscopy, the study shows that, by light excitation, the new hair color group composed by Bpa can be converted almost entirely into a triple state, and in the presence of biologically related sacrificial reducing agent, the triple intermediate rapid lysise sacrifice reducing agent can produce a free radical state.
the free radical is protected by a protein skeleton and therefore can be stable for more than 10 minutes without oxygen present.
crystal structure diffraction shows that when PSP is in a free radical state, its hair color group presents a more expanded conplanus conformation, which is consistent with the redshift absorption results from ultraviolet-visible absorption spectra detection.
on the other hand, the synthetic electrochemical analysis of small molecules containing bpA's hair-color group shows that the resulting free radical state has a reductive potential of close to -1.5V.
this not only meets the need to reduce CO2, but is also lower than the known natural bioreducing agent.
after acquiring the photosensitive protein, the researchers further applied chemical biology methods to introduce a small molecule CO2 electrochemical reduction catalyst, the triamcinolone nickel ferrita, at specific sites on the surface of the PSP protein.
this hybrid protein has the activity of reducing carbon dioxide to produce carbon monoxide under lighting conditions, with a photoquantum yield of 2.6%, higher than most of the reported CO2 photoreducing catalysts.
this indicates the optimization and activity of electron transfer based on the self-assembly properties of proteins.
the photosensitive protein catalyst has the following advantages: 1, no heavy metals;
thus, PSPs are potentially able to bio-photosensitivity a variety of challenging chemical transformations in a variety of fields such as solar energy conversion, photobiology, environmental restoration and industrial biology.
the study was awarded to the National Key Research and Development Program (2017YFA0503704, 2016YFA0501502), The Natural Science Foundation (21750003, 91527302, U1632133, 31628004, 21473237, 31628004, Chinese Academy of Sciences Frontier Project (QYZDB-SSW-SMC032, 15PTCY0020, ZMVS201811092), etc.
Source: Institute of Biophysics
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