A Novel Dialkylamino GFP Chromophore as an Environment-Polarity Sensor Reveals the Role of Twisted Intramolecular Charge Transfer
We discovered a novel fluorophore by incorporating a dimethylamino group (–NMe<sub>2</sub>) into the conformationally locked green fluorescent protein (GFP) scaffold. It exhibited a marked solvent-polarity-dependent fluorogenic behavior and can potentially find broad applications as an e...
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MDPI AG
2021-08-01
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| Series: | Chemosensors |
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| Online Access: | https://www.mdpi.com/2227-9040/9/8/234 |
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| author | Cheng Chen Sean A. Boulanger Anatolii I. Sokolov Mikhail S. Baranov Chong Fang |
| author_facet | Cheng Chen Sean A. Boulanger Anatolii I. Sokolov Mikhail S. Baranov Chong Fang |
| author_sort | Cheng Chen |
| collection | DOAJ |
| description | We discovered a novel fluorophore by incorporating a dimethylamino group (–NMe<sub>2</sub>) into the conformationally locked green fluorescent protein (GFP) scaffold. It exhibited a marked solvent-polarity-dependent fluorogenic behavior and can potentially find broad applications as an environment-polarity sensor in vitro and in vivo. The ultrafast femtosecond transient absorption (fs-TA) spectroscopy in combination with quantum calculations revealed the presence of a twisted intramolecular charge transfer (TICT) state, which is formed by rotation of the –NMe<sub>2</sub> group in the electronic excited state. In contrast to the bright fluorescent state (FS), the TICT state is dark and effectively quenches fluorescence upon formation. We employed a newly developed multivariable analysis approach to the FS lifetime in various solvents and showed that the FS → TICT reaction barrier is mainly modulated by H-bonding capability instead of viscosity of the solvent, accounting for the observed polarity dependence. These deep mechanistic insights are further corroborated by the dramatic loss of fluorogenicity for two similar GFP-derived chromophores in which the rotation of the –NMe<sub>2</sub> group is inhibited by structural locking. |
| first_indexed | 2024-03-10T08:54:29Z |
| format | Article |
| id | doaj.art-53170708cd7a4f0abf61777954f65fdd |
| institution | Directory Open Access Journal |
| issn | 2227-9040 |
| language | English |
| last_indexed | 2024-03-10T08:54:29Z |
| publishDate | 2021-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Chemosensors |
| spelling | doaj.art-53170708cd7a4f0abf61777954f65fdd2023-11-22T07:13:24ZengMDPI AGChemosensors2227-90402021-08-019823410.3390/chemosensors9080234A Novel Dialkylamino GFP Chromophore as an Environment-Polarity Sensor Reveals the Role of Twisted Intramolecular Charge TransferCheng Chen0Sean A. Boulanger1Anatolii I. Sokolov2Mikhail S. Baranov3Chong Fang4Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331, USADepartment of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331, USAInstitute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya 16/10, 117997 Moscow, RussiaInstitute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya 16/10, 117997 Moscow, RussiaDepartment of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, OR 97331, USAWe discovered a novel fluorophore by incorporating a dimethylamino group (–NMe<sub>2</sub>) into the conformationally locked green fluorescent protein (GFP) scaffold. It exhibited a marked solvent-polarity-dependent fluorogenic behavior and can potentially find broad applications as an environment-polarity sensor in vitro and in vivo. The ultrafast femtosecond transient absorption (fs-TA) spectroscopy in combination with quantum calculations revealed the presence of a twisted intramolecular charge transfer (TICT) state, which is formed by rotation of the –NMe<sub>2</sub> group in the electronic excited state. In contrast to the bright fluorescent state (FS), the TICT state is dark and effectively quenches fluorescence upon formation. We employed a newly developed multivariable analysis approach to the FS lifetime in various solvents and showed that the FS → TICT reaction barrier is mainly modulated by H-bonding capability instead of viscosity of the solvent, accounting for the observed polarity dependence. These deep mechanistic insights are further corroborated by the dramatic loss of fluorogenicity for two similar GFP-derived chromophores in which the rotation of the –NMe<sub>2</sub> group is inhibited by structural locking.https://www.mdpi.com/2227-9040/9/8/234polarity sensorgreen fluorescent protein chromophorefluorogenicitytwisted intramolecular charge transferultrafast spectroscopymultivariable analysis |
| spellingShingle | Cheng Chen Sean A. Boulanger Anatolii I. Sokolov Mikhail S. Baranov Chong Fang A Novel Dialkylamino GFP Chromophore as an Environment-Polarity Sensor Reveals the Role of Twisted Intramolecular Charge Transfer Chemosensors polarity sensor green fluorescent protein chromophore fluorogenicity twisted intramolecular charge transfer ultrafast spectroscopy multivariable analysis |
| title | A Novel Dialkylamino GFP Chromophore as an Environment-Polarity Sensor Reveals the Role of Twisted Intramolecular Charge Transfer |
| title_full | A Novel Dialkylamino GFP Chromophore as an Environment-Polarity Sensor Reveals the Role of Twisted Intramolecular Charge Transfer |
| title_fullStr | A Novel Dialkylamino GFP Chromophore as an Environment-Polarity Sensor Reveals the Role of Twisted Intramolecular Charge Transfer |
| title_full_unstemmed | A Novel Dialkylamino GFP Chromophore as an Environment-Polarity Sensor Reveals the Role of Twisted Intramolecular Charge Transfer |
| title_short | A Novel Dialkylamino GFP Chromophore as an Environment-Polarity Sensor Reveals the Role of Twisted Intramolecular Charge Transfer |
| title_sort | novel dialkylamino gfp chromophore as an environment polarity sensor reveals the role of twisted intramolecular charge transfer |
| topic | polarity sensor green fluorescent protein chromophore fluorogenicity twisted intramolecular charge transfer ultrafast spectroscopy multivariable analysis |
| url | https://www.mdpi.com/2227-9040/9/8/234 |
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