[
    {
        "id": "authors:7xt9t-8b578",
        "collection": "authors",
        "collection_id": "7xt9t-8b578",
        "cite_using_url": "https://authors.library.caltech.edu/records/7xt9t-8b578",
        "type": "publication_workingpaper",
        "title": "Application of amber suppression to study the role of Tyr M210 in electron transfer in R. sphaeroides photosynthetic reaction centers",
        "author": [
            {
                "family_name": "Tran",
                "given_name": "Khoi",
                "orcid": "0000-0001-5009-8956"
            },
            {
                "family_name": "Faries",
                "given_name": "Kaitlyn"
            },
            {
                "family_name": "Magdaong",
                "given_name": "Nikki",
                "orcid": "0000-0003-3550-8288"
            },
            {
                "family_name": "Mathews",
                "given_name": "Irimpan"
            },
            {
                "family_name": "Weaver",
                "given_name": "Jared"
            },
            {
                "family_name": "Kirsh",
                "given_name": "Jacob",
                "orcid": "0000-0002-1444-2913",
                "clpid": "Kirsh-Jacob-M"
            },
            {
                "family_name": "Holten",
                "given_name": "Dewey"
            },
            {
                "family_name": "Kirmaier",
                "given_name": "Christine",
                "orcid": "0000-0003-1825-4546"
            },
            {
                "family_name": "Boxer",
                "given_name": "Steven",
                "orcid": "0000-0001-9167-4286"
            }
        ],
        "abstract": "The initial light-induced electron transfer (ET) steps in the bacterial photosynthetic reaction center (RC) have been extensively studied and provide a paradigm for connecting structure and function. Although RCs have local pseudo-C2 symmetry, ET only occurs along the A branch of chromophores. Tyrosine M210 is a key symmetry-breaking residue adjacent to bacteriochlorophyll BA that bridges primary electron donor P and bacteriopheophytin acceptor HA. We used amber suppression to incorporate phenylalanine variants with different electron-withdrawing/donating capabilities at position M210. X-ray data generally reveal no appreciable structural changes due to the mutations. P* decay and P+HA formation are multi-exponential (~2-9, ~10-60, and ~100-300 ps) and temperature dependent. The 1020 nm transient-absorption band of P+BA is barely resolved for a few variants at 295 K and for none at 77 K. The results indicate a change from two-step ET for wild-type RCs to dominance of one-step superexchange ET for the mutants. Resonance Stark spectroscopy reveals that the free energy of P+BA changes by -57 to +66 meV among the phenylalanine variants. Because P+BA apparently lies above P* in all phenylalanine variants, the perturbations primarily affect the energy denominator for superexchange mixing. The findings deepen insight into primary ET in the bacterial RC.",
        "doi": "10.26434/chemrxiv-2024-sc7gr",
        "publisher": "ChemRxiv",
        "publication_date": "2024-12-31"
    }
]