Tuning the Protein-Induced Absorption Shifts of Retinal in Engineered Rhodopsin Mimics.
Rational design of light-capturing properties requires understanding the molecular and electronic structure of chromophores in their native chemical or biological environment. We employ here large-scale quantum chemical calculations to study the light-capturing properties of retinal in recently designed human cellular retinol binding protein II (hCRBPII) variants (Wang et al. Science, 2012, 338, 1340-1343). Our calculations show that these proteins absorb across a large part of the visible spectrum by combined polarization and electrostatic effects. These effects stabilize the ground or excited state energy levels of the retinal by perturbing the Schiff-base or β-ionone moieties of the chromophore, which in turn modulates the amount of charge transfer within the molecule. Based on the predicted tuning principles, we design putative in silico mutations that further shift the absorption properties of retinal in hCRBPII towards the ultraviolet and infrared regions of the spectrum.
Department of Chemistry, University of Helsinki, A.I. Virtanens plats 1, P.O. Box 55, FI-00014, Helsinki, Finland.|Department Chemie, Technische Universität München (TUM), Lichtenbergstrasse 4, 85747, Garching, Germany.
Carl-Mikael
0000-0002-2445-8791
CM
Suomivuori
Department Chemie, Technische Universität München (TUM), Lichtenbergstrasse 4, 85747, Garching, Germany.
Lucas
0000-0002-5796-1641
L
Lang
Department of Chemistry, University of Helsinki, A.I. Virtanens plats 1, P.O. Box 55, FI-00014, Helsinki, Finland.
Dage
D
Sundholm
Department Chemie, Technische Universität München (TUM), Lichtenbergstrasse 4, 85747, Garching, Germany.
Ana P
AP
Gamiz-Hernandez
Department Chemie, Technische Universität München (TUM), Lichtenbergstrasse 4, 85747, Garching, Germany. ville.kaila@ch.tum.de.
Ville R I
VR
Kaila
D006801:Humans; D008958:Models, Molecular; D045792:Norisoprenoids / Q000737:chemistry; D011789:Quantum Theory; D012172:Retinaldehyde / Q000737:chemistry* / Q000378:metabolism; D054840:Retinol-Binding Proteins, Cellular / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012545:Schiff Bases / Q000737:chemistry; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D055672:Static Electricity; D013816:Thermodynamics
D045792:Norisoprenoids; D054840:Retinol-Binding Proteins, Cellular; D012545:Schiff Bases; C008157:beta-ionone; D012172:Retinaldehyde
QM/MM; computational chemistry; density functional calculations; molecular modeling; protein structures; quantum chemistry