Mechanism of Asparagine-Mediated Proton Transfer in Photosynthetic Reaction Centers.

ABSTRACT: In photosynthetic reaction centers from purple bacteria (PbRCs), light-induced charge separation leads to the reduction of the terminal electron acceptor quinone, Q_B. The reduction of Q_B to Q_B^•- is followed by protonation via Asp-L213 and Ser-L223 in PbRC from Rhodobacter sphaeroides. However, Asp-L213 is replaced with nontitratable Asn-L222 and Asn-L213 in PbRCs from Thermochromatium tepidum and Blastochloris viridis, respectively. Here, we investigated the energetics of proton transfer along the asparagine-involved H-bond network using a quantum mechanical/molecular mechanical approach. The potential energy profile for the H-bond between H₃O⁺ and the carbonyl O site of Asn-L222 shows that the proton is

SUBMITTER: Sugo Y 

PROVIDER: S-EPMC10194076 | biostudies-literature | 2023 May

REPOSITORIES: biostudies-literature