Decoding the Structure of Non-Proteinogenic Amino Acids: The Rotational Spectrum of Jet-Cooled Laser-Ablated Thioproline
The broadband rotational spectrum of jet-cooled laser-ablated thioproline was recorded. Two conformers of this system were observed and identified with the help of DFT and ab initio computations by comparison of the observed and calculated rotational constants and <sup>14</sup>N quadrupo...
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| Format: | Article |
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MDPI AG
2021-12-01
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| Series: | Molecules |
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| Online Access: | https://www.mdpi.com/1420-3049/26/24/7585 |
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| author | Juan Carlos López Alberto Macario Andrés Verde Alfonso Pérez-Encabo Susana Blanco |
| author_facet | Juan Carlos López Alberto Macario Andrés Verde Alfonso Pérez-Encabo Susana Blanco |
| author_sort | Juan Carlos López |
| collection | DOAJ |
| description | The broadband rotational spectrum of jet-cooled laser-ablated thioproline was recorded. Two conformers of this system were observed and identified with the help of DFT and ab initio computations by comparison of the observed and calculated rotational constants and <sup>14</sup>N quadrupole coupling constants as well as the predicted energies compared to the observed relative populations. These conformers showed a mixed bent/twisted arrangement of the five-membered ring similar to that of the related compound thiazolidine with the N–H bond in axial configuration. The most stable form had the COOH group in an equatorial position on the same side of the ring as N-H. The arrangement of the C=O group close to the N-H bond led to a weak interaction between them (classified as type I) characterized by a noncovalent interaction analysis. The second form had a <i>trans</i>-COOH arrangement showing a type II O–H···N hydrogen bond. In thioproline, the stability of conformers of type I and type II was reversed with respect to proline. We show how the conformation of the ring depends on the function associated with the endocyclic N atom when comparing the structures of isolated thioproline with its zwitterion observed in condensed phases and with peptide forms. |
| first_indexed | 2024-03-10T03:28:27Z |
| format | Article |
| id | doaj.art-8ff3ef77899c49f2bbfd6bce9d68979f |
| institution | Directory Open Access Journal |
| issn | 1420-3049 |
| language | English |
| last_indexed | 2024-03-10T03:28:27Z |
| publishDate | 2021-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Molecules |
| spelling | doaj.art-8ff3ef77899c49f2bbfd6bce9d68979f2023-11-23T09:46:19ZengMDPI AGMolecules1420-30492021-12-012624758510.3390/molecules26247585Decoding the Structure of Non-Proteinogenic Amino Acids: The Rotational Spectrum of Jet-Cooled Laser-Ablated ThioprolineJuan Carlos López0Alberto Macario1Andrés Verde2Alfonso Pérez-Encabo3Susana Blanco4Departamento de Química Física y Química Inorgánica, Facultad de Ciencias, IU CINQUIMA Universidad de Valladolid, 47011 Valladolid, SpainDepartamento de Química Física y Química Inorgánica, Facultad de Ciencias, IU CINQUIMA Universidad de Valladolid, 47011 Valladolid, SpainDepartamento de Química Física y Química Inorgánica, Facultad de Ciencias, IU CINQUIMA Universidad de Valladolid, 47011 Valladolid, SpainDepartamento de Química Orgánica, Facultad de Ciencias, Universidad de Valladolid, 47011 Valladolid, SpainDepartamento de Química Física y Química Inorgánica, Facultad de Ciencias, IU CINQUIMA Universidad de Valladolid, 47011 Valladolid, SpainThe broadband rotational spectrum of jet-cooled laser-ablated thioproline was recorded. Two conformers of this system were observed and identified with the help of DFT and ab initio computations by comparison of the observed and calculated rotational constants and <sup>14</sup>N quadrupole coupling constants as well as the predicted energies compared to the observed relative populations. These conformers showed a mixed bent/twisted arrangement of the five-membered ring similar to that of the related compound thiazolidine with the N–H bond in axial configuration. The most stable form had the COOH group in an equatorial position on the same side of the ring as N-H. The arrangement of the C=O group close to the N-H bond led to a weak interaction between them (classified as type I) characterized by a noncovalent interaction analysis. The second form had a <i>trans</i>-COOH arrangement showing a type II O–H···N hydrogen bond. In thioproline, the stability of conformers of type I and type II was reversed with respect to proline. We show how the conformation of the ring depends on the function associated with the endocyclic N atom when comparing the structures of isolated thioproline with its zwitterion observed in condensed phases and with peptide forms.https://www.mdpi.com/1420-3049/26/24/7585laser-ablationrotational spectroscopyamino acidscomputational chemistryintramolecular interactions |
| spellingShingle | Juan Carlos López Alberto Macario Andrés Verde Alfonso Pérez-Encabo Susana Blanco Decoding the Structure of Non-Proteinogenic Amino Acids: The Rotational Spectrum of Jet-Cooled Laser-Ablated Thioproline Molecules laser-ablation rotational spectroscopy amino acids computational chemistry intramolecular interactions |
| title | Decoding the Structure of Non-Proteinogenic Amino Acids: The Rotational Spectrum of Jet-Cooled Laser-Ablated Thioproline |
| title_full | Decoding the Structure of Non-Proteinogenic Amino Acids: The Rotational Spectrum of Jet-Cooled Laser-Ablated Thioproline |
| title_fullStr | Decoding the Structure of Non-Proteinogenic Amino Acids: The Rotational Spectrum of Jet-Cooled Laser-Ablated Thioproline |
| title_full_unstemmed | Decoding the Structure of Non-Proteinogenic Amino Acids: The Rotational Spectrum of Jet-Cooled Laser-Ablated Thioproline |
| title_short | Decoding the Structure of Non-Proteinogenic Amino Acids: The Rotational Spectrum of Jet-Cooled Laser-Ablated Thioproline |
| title_sort | decoding the structure of non proteinogenic amino acids the rotational spectrum of jet cooled laser ablated thioproline |
| topic | laser-ablation rotational spectroscopy amino acids computational chemistry intramolecular interactions |
| url | https://www.mdpi.com/1420-3049/26/24/7585 |
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