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Thøgersen J, Madzharova F, Weidner T, Jensen F. Aqueous pyruvate partly dissociates under deep ultraviolet irradiation but is resilient to near ultraviolet excitation. Nat Commun 2024; 15:1978. [PMID: 38438353 PMCID: PMC10912111 DOI: 10.1038/s41467-024-46309-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 02/14/2024] [Indexed: 03/06/2024] Open
Abstract
The deep ultraviolet photochemistry of aqueous pyruvate is believed to have been essential to the origin of life, and near ultraviolet excitation of pyruvate in aqueous aerosols is assumed to contribute significantly to the photochemistry of the Earth's atmosphere. However, the primary photochemistry of aqueous pyruvate is unknown. Here we study the susceptibility of aqueous pyruvate to photodissociation by deep ultraviolet and near ultraviolet irradiation with femtosecond spectroscopy supported by density functional theory calculations. The primary photo-dynamics of the aqueous pyruvate show that upon deep-UV excitation at 200 nm, about one in five excited pyruvate anions have dissociated by decarboxylation 100 ps after the excitation, while the rest of the pyruvate anions return to the ground state. Upon near-UV photoexcitation at a wavelength of 340 nm, the dissociation yield of aqueous pyruvate 200 ps after the excitation is insignificant and no products are observed. The experimental results are explained by our calculations, which show that aqueous pyruvate anions excited at 200 nm have sufficient excess energy for decarboxylation, whereas excitation at 340 nm provides the aqueous pyruvate anions with insufficient energy to overcome the decarboxylation barrier.
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Affiliation(s)
- Jan Thøgersen
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000, Aarhus C, Denmark
| | - Fani Madzharova
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000, Aarhus C, Denmark
| | - Tobias Weidner
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000, Aarhus C, Denmark
| | - Frank Jensen
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000, Aarhus C, Denmark.
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Thøgersen J, Chatterley AS, Weidner T, Jensen F. Peptide Bond of Aqueous Dipeptides Is Resilient to Deep Ultraviolet Irradiation. J Am Chem Soc 2023; 145:9777-9785. [PMID: 37075197 DOI: 10.1021/jacs.3c01469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/21/2023]
Abstract
The susceptibility of aqueous dipeptides to photodissociation by deep ultraviolet irradiation is studied by femtosecond spectroscopy supported by density functional theory calculations. The primary photodynamics of the aqueous dipeptides of glycyl-glycine (gly-gly), alalyl-alanine (ala-ala), and glycyl-alanine (gly-ala) show that upon photoexcitation at a wavelength of 200 nm, about 10% of the excited dipeptides dissociate by decarboxylation within 100 ps, while the rest of the dipeptides return to their native ground state. Accordingly, the vast majority of the excited dipeptides withstand the deep ultraviolet excitation. In those relatively few cases, where excitation leads to dissociation, the measurements show that deep ultraviolet irradiation breaks the Cα-C bond rather than the peptide bond. The peptide bond is thereby left intact, and the decarboxylated dipeptide moiety is open to subsequent reactions. The experiments indicate that the low photodissociation yield and in particular the resilience of the peptide bond to dissociation are due to rapid internal conversion from the excited state to the ground state, followed by efficient vibrational relaxation facilitated by intramolecular coupling among the carbonate and amide modes. Thus, the entire process of internal conversion and vibrational relaxation to thermal equilibrium on the dipeptide ground state occurs on a time scale of less than 2 ps.
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Affiliation(s)
- Jan Thøgersen
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Adam S Chatterley
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Tobias Weidner
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Frank Jensen
- Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
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Qiu Z, Zheng Z, Song Z, Sun Y, Shan Q, Lin Z, Xie Z. Co 3O 4 nanocrystals as matrices for the detection of amino acids, harmful additives and pesticide residues by MALDI-TOF MS. Talanta 2022; 242:123299. [PMID: 35183982 DOI: 10.1016/j.talanta.2022.123299] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Revised: 01/29/2022] [Accepted: 02/04/2022] [Indexed: 01/04/2023]
Abstract
Research of detection of low molecular weight compounds on human health and biological systems become increasingly important. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), a soft ionization equipment, is a rapid, reliable, high-sensitivity, high-throughput and simple test instrument. However, the application of MALDI-TOF MS in the analysis of small molecules (<500 Da) has become a great challenge because of the interference from the conventional matrices in low mass region when using conventional matrices. In this research, tricobalt tetraoxide (Co3O4) nanocrystals with rich surface hydroxyl groups were synthesized and served as novel matrices for the detection of small molecules by MALDI-TOF MS. In comparison with conventional organic matrices, the use of as-prepared Co3O4 nanocrystal matrices showed little matrix background interference, good reproducibility and high signal intensity in the analyses of amino acids, harmful additives and pesticide residues. For the detection of most amino acids, Co3O4 nanocrystal matrices have good detection performance both in the positive and negative ion modes and have a unique decarboxylation peak in the positive ion mode, which is conducive to the identification of amino acids. In addition, Co3O4 nanocrystals are completely feasible to test triadimefon, pirimicarb and other pesticide residues, as well as additives such as bisphenol A and melamine in the positive ion mode. It is also feasible to detect small molecule compounds in practical samples using Co3O4 nanocrystals as matrices. We believe the work provides an alternative approach for the detection of small molecules and expands the application scope of Co3O4 nanocrystals.
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Affiliation(s)
- Zufeng Qiu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Zhiping Zheng
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Zhijia Song
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Yunchao Sun
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Qiheng Shan
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
| | - Zhiwei Lin
- Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China.
| | - Zhaoxiong Xie
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China; Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361005, China.
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ThOgersen J, Weidner T, Jensen F. The primary photo-dissociation dynamics of aqueous formamide and dimethylformamide. Phys Chem Chem Phys 2022; 24:24695-24705. [DOI: 10.1039/d2cp03166c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We study the primary dissociation dynamics of aqueous formamide (HCONH2) and dimethylformamide (HCON(CH3)2) induced by photo-excitation at λ = 200 nm. The photolysis is recorded with sub-picosecond time resolution by...
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Thøgersen J, Vaida V, Bregnhøj M, Weidner T, Jensen F. The primary photo-dissociation dynamics of lactate in aqueous solution: decarboxylation prevents dehydroxylation. Phys Chem Chem Phys 2021; 23:4555-4568. [PMID: 33605952 DOI: 10.1039/d0cp05650b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We study the primary photolysis dynamics of aqueous lactate induced by photo-excitation at λ = 200 nm. Our calculations indicate that both decarboxylation and dehydroxylation are energetically possible, but decarboxylation is favoured dynamically. UV pump - IR probe transient absorption spectroscopy shows that the photolysis is dominated by decarboxylation, whereas dehydroxylation is not observed. Analysis of the transient IR spectrum suggests that photo-dissociation of lactate primarily produces CO2 and CH3CHOH- through the lowest singlet excited state of lactate, which has a lifetime of τ = 11 ps. UV pump - VIS probe transient absorption spectroscopy of electrons from the dissociating lactate anion indicates that the anionic electron from the CO2˙- fragment is transferred to the CH3CHOH˙ counter radical during the decarboxylation process, and CO2˙- is consequently only observed as a minor photo-product. The photo-dissociation quantum yield after the full decay of the excited state is Φ(100ps) = 38 ± 5%.
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Affiliation(s)
- Jan Thøgersen
- Dept. of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark.
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Thøgersen J, Weidner T, Jensen F. The primary photolysis dynamics of oxalate in aqueous solution: decarboxylation. Phys Chem Chem Phys 2021; 23:10040-10050. [PMID: 33870982 DOI: 10.1039/d1cp00205h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We study the primary reaction dynamics of aqueous oxalate following photo-excitation of the nO → πCO* transition at λ = 200 nm. After the excitation, some of the oxalate molecules return to the electronic ground state on two very different time scales: a fast component of τ = 1.1 ± 0.5 ps comprising 40% of the excited molecules and a much slower component of τ = 0.28 ± 0.05 ns accounting for 15% of the excited molecules. The remaining 45% of the excited molecules do not return to the ground state during the first 500 ps, because they either detach an electron, dissociate or stay excited for hundreds of picoseconds. Dissociation and electron detachment of oxalate predominantly produces CO2 molecules with only minor yields of CO2˙- radical anions. The CO2 formation is accompanied by the ejection of electrons.
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Affiliation(s)
- Jan Thøgersen
- Dept. of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark.
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