Photoinduced electron transfer from aromatic amino acids to the excited isoalloxazine in single mutated flavin mononucleotide binding proteins: Effect of the dimer formation on the rate and the electrostatic energy inside the proteins

Publication date: Available online 7 March 2017 Source:Computational and Theoretical Chemistry Author(s): Nadtanet Nunthaboot, Kiattisak Lugsanangarm, Arthit Nueangaudom, Somsak Pianwanit, Sirirat Kokpol, Fumio Tanaka, Seiji Taniguchi, Haik Chosrowjan, Takeshi Nakanishi, Masaya Kitamura Conformational changes in the single mutated flavin mononucleotide binding proteins (FBP), E13K (Glu13 of wild type FBP is replaced by Lys), E13R (Glu13 replaced by Arg), E13T (Glu13 replaced by Thr) and E13Q (Glu13 replaced by Gln) upon dimer formations were studied through the phenomena of photoinduced electron transfer (ET) from tryptophan 32 (Trp32) and tryptophan 106 (Trp106) to the excited isoalloxazine (Iso∗). The ET rates were obtained with atomic coordinates of the proteins determined by a method of molecular dynamics simulation (MDS) and an ET theory using the reported experimental fluorescence decays of the FBPs. The value of the net electrostatic energy (NetES) between the photo-products and ionic groups inside the proteins increased in magnitude upon the dimer formation in every mutated FBP. Dependencies in the logarithmic ET rate (ln Rate) on the donor-acceptor distances (Rc) could not be approximated with simple linear nor parabolic functions in most ET donors, which are ascribed to the relatively greater values of the NetES in the dimers compared to the energy terms of the standard free energy gap (SFEG), solvent reorganization energy (SROE) and the electrostatic ...

Source: Computational and Theoretical Chemistry - March 7, 2017 Category: Chemistry Source Type: research