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Duncan KM, Trousdale RC, Gonzales CN, Steel WH, Walker RA. l-Phenylalanine Partitioning Mechanisms in Model Biological Membranes. J Phys Chem B 2023. [PMID: 37315336 DOI: 10.1021/acs.jpcb.2c08582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Time-resolved fluorescence spectroscopy in combination with differential scanning calorimetry (DSC) was used to study the chemical interactions that occur when l-phenylalanine is introduced to solutions containing phosphatidylcholine vesicles. Studies reported in this work address open questions about l-Phe's affinity for lipid vesicle bilayers, the effects of l-Phe partitioning on bilayer properties, l-Phe's solvation within a lipid bilayer, and the amount of l-Phe within that local solvation environment. DSC data show that l-Phe reduces the amount of heat necessary to melt saturated phosphatidylcholine bilayers from their gel to liquid-crystalline state but does not change the transition temperature (Tgel-lc). Time-resolved emission shows only a single l-Phe lifetime at low temperatures corresponding to l-Phe remaining solvated in aqueous solution. At temperatures close to Tgel-lc, a second, shorter lifetime appears that is assigned to l-Phe already embedded within the membrane that becomes hydrated as water starts to permeate the lipid bilayer. This new lifetime is attributed to a conformationally restricted rotamer in the bilayer's polar headgroup region and accounts for up to 30% of the emission amplitude. Results reported for dipalmitoylphosphatidylcholine (DPPC, 16:0) lipid vesicles prove to be general, with similar effects observed for dimyristoylphosphatidylcholine (DMPC, 14:0) and distearoylphosphatidylcholine (DSPC, 18:0) vesicles. Taken together, these results create a complete and compelling picture of how l-Phe associates with model biological membranes. Furthermore, this approach to examining amino acid partitioning into membranes and the resulting solvation forces points to new strategies for studying the structure and chemistry of membrane-soluble peptides and selected membrane proteins.
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Affiliation(s)
- Katelyn M Duncan
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Rhys C Trousdale
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Cristina N Gonzales
- Department of Chemistry, Reed College, Portland, Oregon 97202, United States
| | - William H Steel
- Department of Chemistry, York College of Pennsylvania, York, Pennsylvania 17403, United States
| | - Robert A Walker
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
- Montana Materials Science Program, Montana State University, Bozeman, Montana 59717, United States
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Zhang Y, Duy SV, Whalen JK, Munoz G, Gao X, Sauvé S. Cyanotoxins dissipation in soil: Evidence from microcosm assays. JOURNAL OF HAZARDOUS MATERIALS 2023; 454:131534. [PMID: 37146322 DOI: 10.1016/j.jhazmat.2023.131534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 04/18/2023] [Accepted: 04/27/2023] [Indexed: 05/07/2023]
Abstract
Cyanobacteria proliferate in warm, nutrient-rich environments, and release cyanotoxins into natural waters. If cyanotoxin-contaminated water is used to irrigate agricultural crops, this could expose humans and other biota to cyanotoxins. However, cyanotoxins may be degraded by the diverse microbial consortia, be adsorbed or otherwise dissipate in agricultural soil. This study investigates the disappearance and transformation of 9 cyanotoxins in controlled soil microcosms after 28 d. Six soil types were exposed to factorial combinations of light, redox conditions and microbial activity that influenced the recovery of anabaenopeptin-A (AP-A), anabaenopeptin-B (AP-B), anatoxin-a (ATX-a), cylindrospermopsin (CYN), and the microcystin (MC) congeners -LR, -LA, -LY, -LW, and -LF. Cyanotoxins estimated half-lives were from hours to several months, depending on the compound and soil conditions. Cyanotoxins were eliminated via biological reactions in aerobic and anaerobic soils, although anaerobic conditions accelerated the biological dissipation of ATX-a, CYN and APs. ATX-a was sensitive to photolytic degradation, but CYN, and MCs were not reduced through photochemical transformation. MC-LR and -LA were recovered after exposure to light, redox conditions and low microbial activity, suggesting that they persisted in extractable forms, compared to other cyanotoxins in soil. Cyanotoxin degradation products were identified using high-resolution mass spectrometry, revealing their potential degradation pathways in soil.
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Affiliation(s)
- Yanyan Zhang
- State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China; College of Resources, Sichuan Agricultural University, 211 Huimin Rd., Chengdu 611130, China; Department of Chemistry, Université de Montréal, Campus MIL, 1375 Av. Thérèse-Lavoie-Roux, Montréal, QC H2V 0B3, Canada; Department of Natural Resource Sciences, McGill University, Macdonald Campus, 21,111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada; Key Laboratory of Investigation and Monitoring, Protection and Utilization for Cultivated Land Resources, Ministry of Natural Resources, China.
| | - Sung Vo Duy
- Department of Chemistry, Université de Montréal, Campus MIL, 1375 Av. Thérèse-Lavoie-Roux, Montréal, QC H2V 0B3, Canada
| | - Joann K Whalen
- Department of Natural Resource Sciences, McGill University, Macdonald Campus, 21,111 Lakeshore Road, Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada
| | - Gabriel Munoz
- Department of Chemistry, Université de Montréal, Campus MIL, 1375 Av. Thérèse-Lavoie-Roux, Montréal, QC H2V 0B3, Canada
| | - Xuesong Gao
- State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China; College of Resources, Sichuan Agricultural University, 211 Huimin Rd., Chengdu 611130, China; Key Laboratory of Investigation and Monitoring, Protection and Utilization for Cultivated Land Resources, Ministry of Natural Resources, China
| | - Sébastien Sauvé
- Department of Chemistry, Université de Montréal, Campus MIL, 1375 Av. Thérèse-Lavoie-Roux, Montréal, QC H2V 0B3, Canada
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Bin Mohd Yusof MS, Siow JX, Yang N, Chan WX, Loh ZH. Spectroscopic observation and ultrafast coherent vibrational dynamics of the aqueous phenylalanine radical. Phys Chem Chem Phys 2022; 24:2800-2812. [PMID: 35048090 DOI: 10.1039/d1cp04326a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The phenylalanine radical (Phe˙) has been proposed to mediate biological electron transport (ET) and exhibit long-lived electronic coherences following attosecond photoionization. However, the coupling of ultrafast structural reorganization to the oxidation/ionization of biomolecules such as phenylalanine remains unexplored. Moreover, studies of ET involving Phe˙ are hindered by its hitherto unobserved electronic spectrum. Here, we report the spectroscopic observation and coherent vibrational dynamics of aqueous Phe˙, prepared by sub-6 fs photodetachment of phenylalaninate anions. Sub-picosecond transient absorption spectroscopy reveals the ultraviolet absorption signature of Phe˙. Ultrafast structural reorganization drives coherent vibrational motion involving nine fundamental frequencies and one overtone. DFT calculations rationalize the absence of the decarboxylation reaction, a photodegradation pathway previously identified for Phe˙. Our findings guide the interpretation of future attosecond experiments aimed at elucidating coherent electron motion in photoionized aqueous biomolecules and pave way for the spectroscopic identification of Phe˙ in studies of biological ET.
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Affiliation(s)
- Muhammad Shafiq Bin Mohd Yusof
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
| | - Jing Xuan Siow
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
| | - Ningchen Yang
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
| | - Wei Xin Chan
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
| | - Zhi-Heng Loh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
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Phenylalanine Photoinduced Fluorescence and Characterization of the Photoproducts by LC-MS. J Fluoresc 2019; 29:1445-1455. [DOI: 10.1007/s10895-019-02449-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 10/01/2019] [Indexed: 10/25/2022]
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5
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Photocatalysis of viologens for photoinitiated polymerization using carboxylic acid as electron donors. J Photochem Photobiol A Chem 2017. [DOI: 10.1016/j.jphotochem.2016.10.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Barondeau DP, Kassmann CJ, Tainer JA, Getzoff ED. The Case of the Missing Ring: Radical Cleavage of a Carbon−Carbon Bond and Implications for GFP Chromophore Biosynthesis. J Am Chem Soc 2007; 129:3118-26. [PMID: 17326633 DOI: 10.1021/ja063983u] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The green fluorescent protein (GFP) creates its fluorophore by promoting spontaneous peptide backbone cyclization and amino acid oxidation chemistry on its own Ser65, Tyr66, Gly67 tripeptide sequence. Here we use high-resolution crystallography and mutational analyses to characterize GFP variants that undergo backbone cyclization followed by either anticipated chromophore synthesis via Y66F Calpha-Cbeta double-bond formation or unprecedented loss of a Y66F benzyl moiety via Calpha-Cbeta bond cleavage. We discovered a Y66F cleavage variant that subsequently incorporates an oxygen atom, likely from molecular oxygen, at the Y66 Calpha position. The post-translational products identified from these Y66F GFP structures support a common intermediate that partitions between Calpha-Cbeta oxidation and homolytic cleavage pathways. Our data indicate that Glu222 is the branchpoint control for this partitioning step and also influences subsequent oxygen incorporation reactions. From these results, we propose mechanisms for Y66F Calpha-Cbeta cleavage, oxygen incorporation, and chromophore biosynthesis with shared features that include radical chemistry. By revealing how GFP and RFP protein environments steer chemistry to favor fluorophore biosynthesis and disfavor alternative reactivity, we identify strategies for protein design. The proposed, common, one-electron oxidized, radical intermediate for post-translation modifications in the GFP family has general implications for how proteins drive and control spontaneous post-translational chemical modifications in the absence of metal ions.
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Affiliation(s)
- David P Barondeau
- Department of Molecular Biology, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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Mohanty J, Pal H, Saini RD, Sapre AV, Mittal JP. Triplet-State Characteristics and Photoionization Behavior of 2,2‘- and 4,4‘-Biphenyldiol Studied by 248 nm Laser Flash Photolysis in Aqueous Solutions. J Phys Chem A 2001. [DOI: 10.1021/jp012445v] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- J. Mohanty
- Radiation Chemistry & Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - H. Pal
- Radiation Chemistry & Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - R. D. Saini
- Radiation Chemistry & Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - A. V. Sapre
- Radiation Chemistry & Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
| | - J. P. Mittal
- Radiation Chemistry & Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
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9
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Mittal LJ, Mittal JP. Pulse radiolysis and flash photolysis studies of arylalkylamines in aqueous solutions — primary photoprocesses. J Photochem Photobiol A Chem 1997. [DOI: 10.1016/s1010-6030(97)89689-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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10
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Ghosh HN, Sapre AV, Palit DK, Mittal JP. Picosecond Flash Photolysis Studies on Phenothiazine in Organic and Micellar Solution. J Phys Chem B 1997. [DOI: 10.1021/jp963028z] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Bhasikuttan AC, Sapre AV, Rao KVSR, Mittal JP. PHOTOIONIZATION OF CRYSTAL VIOLET IN AQUEOUS SOLUTION. Photochem Photobiol 1995. [DOI: 10.1111/j.1751-1097.1995.tb05265.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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12
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Jin F, Leitich J, von Sonntag C. Photolysis (λ = 254 nm) of phenylalanine in aqueous solution. J Photochem Photobiol A Chem 1995. [DOI: 10.1016/1010-6030(94)03895-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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13
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Dou L, Krull IS. Identification of photochemical products of amino acids, peptides, and proteins in on-line, postcolumn photolytic derivatization detection by HPLC-electrochemistry. ELECTROANAL 1992. [DOI: 10.1002/elan.1140040405] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Lion Y, Kuwabara M, Riesz P. SPIN-TRAPPING AND ESR STUDIES OF THE DIRECT PHOTOLYSIS OF AROMATIC AMINO ACIDS, DIPEPTIDES, TRIPEPTIDES AND POLYPEPTIDES IN AQUEOUS SOLUTIONS—I. PHENYLALANINE AND RELATED COMPOUNDS. Photochem Photobiol 1981. [DOI: 10.1111/j.1751-1097.1981.tb09001.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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15
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Schaich KM. Free radical initiation in proteins and amino acids by ionizing and ultraviolet radiations and lipid oxidation--Part 22: ultraviolet radiation and photolysis. Crit Rev Food Sci Nutr 1980; 13:131-59. [PMID: 7418432 DOI: 10.1080/10408398009527287] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Parallels and similarities in chemical and functional damage to proteins by ionizing and UV radiations and oxidizing lipids have been recognized for some time. However, only recently have oxidizing lipids been shown directly by electron spin resonance to be radiomimetic also in their capacity for protein free radical production. Free radicals play a key role in the transformation of energy to molecular and cellular damage. It is thus of critical importance to elucidate the general mechanisms of free radical formation and reactions in proteins in order to understand protein involvement in various pathological conditions and in food deterioration. Accordingly, this review is a detailed comparison of gamma radiation, UV radiation, and lipid oxidation for what is presently known concerning (1) the specific modes of energy deposition and free radical formation, (2) the free radicals formed in proteins and amino acids, and (3) the typical damage correlating with these radicals.
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16
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Truong TB. Charge transfer to a solvent. II. Luminescence studies of tryptophan in aqueous solvent at 300 and 77 K. J Chem Phys 1979. [DOI: 10.1063/1.437890] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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17
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Tournon J, Abu-Elgheit M, Avouris P, El-Bayoumi M. Intramolecular interactions and luminescence properties of rigid and non-rigid phenylalkylcarboxylic acids. Chem Phys Lett 1974. [DOI: 10.1016/0009-2614(74)80383-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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