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| Format: | Preprint |
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2024
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| Online-Zugang: | https://arxiv.org/abs/2405.14579 |
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| _version_ | 1866915940869865472 |
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| author | Pidgeon, James P. Sutherland, George A. Proctor, Matthew S. Wang, Shuangqing Chekulaev, Dimitri Bhattacharya, Sayantan Jayaprakash, Rahul Hitchcock, Andrew Venkatraman, Ravi Kumar Johnson, Matthew P. Hunter, C. Neil Clark, Jenny |
| author_facet | Pidgeon, James P. Sutherland, George A. Proctor, Matthew S. Wang, Shuangqing Chekulaev, Dimitri Bhattacharya, Sayantan Jayaprakash, Rahul Hitchcock, Andrew Venkatraman, Ravi Kumar Johnson, Matthew P. Hunter, C. Neil Clark, Jenny |
| contents | The orange carotenoid protein (OCP) is the water-soluble mediator of non-photochemical quenching in cyanobacteria, a crucial photoprotective mechanism in response to excess illumination. OCP converts from a dark-adapted inactive state (OCPo) to an active quenching conformation (OCPr) under high-light conditions, resulting in a concomitant redshift in the absorption of the bound carotenoid. Here, we test whether a long-lived carotenoid singlet excited state (S*) is required for this photoconversion. We measured pump wavelength-dependent transient absorption of OCPo trapped in trehalose-sucrose glass films. We found that initial OCP photoproducts are still formed despite the glass preventing completion to OCPr, and that S* is only apparent for <495 nm pumps. By comparison to the pump wavelength-dependence of the OCPo to OCPr conversion in buffer, we show that S* is not required for photoconversion, and that S* likely arises from ground-state heterogeneity within OCPo. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2405_14579 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Assessment of S* in the Orange Carotenoid Protein Pidgeon, James P. Sutherland, George A. Proctor, Matthew S. Wang, Shuangqing Chekulaev, Dimitri Bhattacharya, Sayantan Jayaprakash, Rahul Hitchcock, Andrew Venkatraman, Ravi Kumar Johnson, Matthew P. Hunter, C. Neil Clark, Jenny Chemical Physics The orange carotenoid protein (OCP) is the water-soluble mediator of non-photochemical quenching in cyanobacteria, a crucial photoprotective mechanism in response to excess illumination. OCP converts from a dark-adapted inactive state (OCPo) to an active quenching conformation (OCPr) under high-light conditions, resulting in a concomitant redshift in the absorption of the bound carotenoid. Here, we test whether a long-lived carotenoid singlet excited state (S*) is required for this photoconversion. We measured pump wavelength-dependent transient absorption of OCPo trapped in trehalose-sucrose glass films. We found that initial OCP photoproducts are still formed despite the glass preventing completion to OCPr, and that S* is only apparent for <495 nm pumps. By comparison to the pump wavelength-dependence of the OCPo to OCPr conversion in buffer, we show that S* is not required for photoconversion, and that S* likely arises from ground-state heterogeneity within OCPo. |
| title | Assessment of S* in the Orange Carotenoid Protein |
| topic | Chemical Physics |
| url | https://arxiv.org/abs/2405.14579 |