2 research outputs found
The protein environment restricts the intramolecular charge transfer character of the luciferine/luciferase complex
The electronic characterization of the luciferine/luciferase complex is fundamental to tune its
photophysical properties and develop more efficient devices based on this luminiscent system. Here, we
apply molecular dynamics simulations, hybrid quantum mechanics/molecular mechanics (QM/MM)
calculations and transition density analysis to compute the absorption and emission spectra of
luciferine/luciferase and analyze the nature of the relevant electronic state and its behaviour with the
intramolecular and intermolecular degrees of freedom. It is found that the torsional motion of the
chromophore is hampered by the presence of the enzyme, reducing the intramolecular charge transfer
nature of the absorbing and emitting state. In addition, such a reduced charge transfer character does
not correlate in a strong way neither with the intramolecular motion of the chromophore nor with the
chromophore/amino-acid distances. However, the presence of a polar environment around the oxygen
atom of the thiazole ring of the oxyluciferin, coming from both the protein and the solvent, enhances
the charge transfer character of the emitting stateWe thank
the support of the Spanish Ministry of Science and Innovation through the project PID2020-117806GA-I00 funded by
MCIN/AEI/10.13039/501100011033, the Comunidad de Madrid
through the Attraction of Talent Program (Grant ref 2018-T1/
BMD-10261) and the Universidad AutĂłnoma de Madrid
through the Ayudas para el Fomento de la InvestigaciĂłn en
Estudios de Master program and the predoctoral Contract
FormaciĂłn de Personal Investigador (FPI-UAM). The work has
been performed under the Project HPC-EUROPA3 (INFRAIA2016-1-730897), with the support of the EC Research Innovation
Action under the H2020 Programme and the CINECA computing center. D.A. and M.G thank funding from the European
Union’s Horizon 2020 research and innovation program under
the H2020-NMBP-TO-IND-2018-2020/DT-NMBP-09-2018 grant
agreement No. 814492 (SIMDOME
MoBioTools: a toolkit to setup quantum mechanics/molecular mechanics calculations
We present a toolkit that allows for the preparation of QM/MM input files from a
conformational ensemble of molecular geometries. The package is currently compatible with trajectory and topology files in Amber, CHARMM, GROMACS and NAMD
formats, and has the possibility to generate QM/MM input files for Gaussian (09 and
16), Orca (≥4.0), NWChem and (Open)Molcas. The toolkit can be used in command
line, so that no programming experience is required, although it presents some features that can also be employed as a python application programming interface. We
apply the toolkit in four situations in which different electronic-structure properties
of organic molecules in the presence of a solvent or a complex biological environment are computed: the reduction potential of the nucleobases in acetonitrile, an
energy decomposition analysis of tyrosine interacting with water, the absorption
spectrum of an azobenzene derivative integrated into a voltage-gated ion channel,
and the absorption and emission spectra of the luciferine/luciferase complex.
These examples show that the toolkit can be employed in a manifold of situations
for both the electronic ground state and electronically excited states. It also allows
for the automatic correction of the active space in the case of CASSCF calculations
on an ensemble of geometries, as it is shown for the azobenzene derivative
photoswitch caseSpanish Ministry of Science and Innovation;
MCIN/AEI, Grant/Award Numbers:
PID2020-117806GA-I00,
PID2019-110091GB-I00; MarĂa de Maeztu,
Grant/Award Number: CEX2018-000805-M;
Comunidad de Madrid, Grant/Award Number:
2018-T1/BMD-10261; Xunta de Galicia,
Grant/Award Number: GRC2019/24; the
European Social Fund; Spanish Ministry of
Education and Vocational Training,
Grant/Award Number: FPU19/02292;
Universidade de Vigo, Grant/Award Number:
PREUVIGO-21; Universidad Autonoma de
Madri