Retinal Photoisomerization in Rhodopsin: Electrostatic and Steric Catalysis
- Dipartimento di Chimica 'G. Ciamician', Universita di Bologna, Via F. Selmi, 2, 40126 Bologna (Italy)
Excited state QM(CASPT2//CASSCF)/MM(GAFF) calculations, by our recently developed code COBRAMM (Computations at Bologna Relating Ab-initio and Molecular Mechanic Methods), were carried out in rhodopsin to investigate on the steric and electrostatic effects in retinal photoisomerization catalysis due to the {beta}-ionone ring and glutammate 181 (GLU 181), respectively. The excited state photoisomerization channel has been mapped and a new christallographyc structure (2.2 Aa resolution) has been used for this purpose. Two different set-ups have been used to evaluate the electrostatic effects of GLU 181 (which is very close to the central double bond of the chromophore): the first with a neutral GLU 181 (as commonly accepted), the second with a negatively charged (i.e. deprotonated) GLU 181 (as very recent experimental findings seem to suggest). On the other hand, {beta}-ionone ring steric effects were evaluated by calculating the photoisomerization path of a modified chromophore, where the ring double bond has been saturated. Spectroscopic properties were calculated and compared with the available experimental data.
- OSTI ID:
- 21043544
- Journal Information:
- AIP Conference Proceedings, Vol. 963, Issue 2; Conference: ICCMSE 2007: International conference on computational methods in science and engineering, Corfu (Greece), 25-30 Sep 2007; Other Information: DOI: 10.1063/1.2836192; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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