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A model to understand type I oxidations of biomolecules photosensitized by pterins. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY 2021. [DOI: 10.1016/j.jpap.2021.100045] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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Dantola ML, Reid LO, Castaño C, Lorente C, Oliveros E, Thomas AH. Photosensitization of peptides and proteins by pterin derivatives. Pteridines 2017. [DOI: 10.1515/pterid-2017-0013] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Abstract
Proteins are one of the preferential targets of the photosensitized damaging effects of ultraviolet (UV) radiation on biological system. Pterins belong to a family of heterocyclic compounds, which are widespread in living systems and participate in relevant biological functions. In pathological conditions, such as vitiligo, oxidized pterins accumulate in the white skin patches of patients suffering this depigmentation disorder. It is known that pterins are able to photosensitize damage in nucleotides and DNA by type I (electron transfer) and type II (singlet oxygen) mechanisms. Recently, it has been demonstrated that proteins and its components may also be damaged when solutions containing both proteins and pterin are exposed to UV-A radiation. Therefore, given the biological and medical relevance of the photosensitizing properties of these molecules, we present in this article an overview of the capability of different pterin derivatives to photoinduce damage in proteins present in the skin, focusing our attention on the chemical modifications of tyrosine and tryptophan residues.
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Affiliation(s)
- Maria Laura Dantola
- Facultad de Ciencias Exactas, Departamento de Química, Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA) , Universidad Nacional de La Plata, CCT La Plata-CONICET , Casilla de Correo 16, Sucursal 4 , 1900 La Plata , Argentina
| | - Lara O. Reid
- Facultad de Ciencias Exactas, Departamento de Química, Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA) , Universidad Nacional de La Plata, CCT La Plata-CONICET , Casilla de Correo 16, Sucursal 4 , 1900 La Plata , Argentina
| | - Carolina Castaño
- Facultad de Ciencias Exactas, Departamento de Química, Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA) , Universidad Nacional de La Plata, CCT La Plata-CONICET , Casilla de Correo 16, Sucursal 4 , 1900 La Plata , Argentina
| | - Carolina Lorente
- Facultad de Ciencias Exactas, Departamento de Química, Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA) , Universidad Nacional de La Plata, CCT La Plata-CONICET , Casilla de Correo 16, Sucursal 4 , 1900 La Plata , Argentina
| | - Esther Oliveros
- Laboratoire des Interactions Moléculaires et Réactivité Chimique et Photochimique (IMRCP), UMR 5623-CNRS/UPS , Université Toulouse III (Paul Sabatier ), 118, route de Narbonne , F-31062 Toulouse Cédex 9 , France
| | - Andrés H. Thomas
- Facultad de Ciencias Exactas, Departamento de Química, Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA) , Universidad Nacional de La Plata, CCT La Plata-CONICET , Casilla de Correo 16, Sucursal 4 , 1900 La Plata , Argentina
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Laura Dántola M, Zurbano BN, Thomas AH. Photoinactivation of tyrosinase sensitized by folic acid photoproducts. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2015; 149:172-9. [DOI: 10.1016/j.jphotobiol.2015.06.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 05/11/2015] [Accepted: 06/03/2015] [Indexed: 02/08/2023]
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Buglak AA, Telegina TA, Lyudnikova TA, Vechtomova YL, Kritsky MS. Photooxidation of tetrahydrobiopterin under UV irradiation: possible pathways and mechanisms. Photochem Photobiol 2014; 90:1017-26. [PMID: 24773158 DOI: 10.1111/php.12285] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 04/24/2014] [Indexed: 12/16/2023]
Abstract
Tetrahydrobiopterin (H4 Bip) is a cofactor for several key enzymes, including NO synthases and aromatic amino acid hydroxylases (AAHs). Normal functioning of the H4 Bip regeneration cycle is extremely important for the work of AAHs. Oxidized pterins may accumulate if the H4 Bip regeneration cycle is disrupted or if H4 Bip autoxidation occurs. These oxidized pterins can photosensitize the production of singlet molecular oxygen (1)O2 and thus cause oxidative stress. In this context, we studied the photooxidation of H4 Bip in phosphate buffer at pH 7.2. We found that UV irradiation of H4 Bip affected its oxidation rate (quantum yield Φ300 = (2.7 ± 0.4) × 10(-3)). The effect of UV irradiation at λ = 350 nm on H4 Bip oxidation was stronger, especially in the presence of biopterin (Bip) (Φ350 = (9.7 ± 1.5) × 10(-3)). We showed that the rate of H4 Bip oxidation linearly depends on Bip concentration. Experiments with KI, a selective quencher of triplet pterins at micromolar concentrations, demonstrated that the oxidation is sensitized by the triplet state biopterin (3) Bip. Apparently, electron transfer sensitization (Type-I mechanism) is dominant. Energy transfer (Type-II mechanism) and singlet oxygen generation play only a secondary role. The mechanisms of H4 Bip photooxidation and their biological meaning are discussed.
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Affiliation(s)
- Andrey A Buglak
- A. N. Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow, Russia
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Determination of pteridines in biological samples with an emphasis on their stability. Bioanalysis 2013; 5:2307-26. [DOI: 10.4155/bio.13.194] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Pteridines are a group of endogenous heterocyclic compounds whose concentrations in biological fluids may be increased in some disorders, such as infections, autoimmune disorders and cancer. In particular, pteridine concentrations in urine may represent promising noninvasive markers. However, their specificity requires further investigation. Pteridines can occur in three oxidation states with different stability. In order to enable the analysis of the unstable di- and tetra-hydroforms either an oxidation (mainly with iodine) or stabilization by reducing agents is applied. Due to the high polarity of pteridines, many analytical procedures employed ion-pair, ion-exchange or hydrophilic interaction liquid chromatography using mostly fluorescence detection. In the last decade, MS was found to be applicable. The objective of this Review is to show possibilities and different approaches in pteridine analysis in biological samples.
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Mortensen A, Lykkesfeldt J. Kinetics of acid-induced degradation of tetra- and dihydrobiopterin in relation to their relevance as biomarkers of endothelial function. Biomarkers 2013; 18:55-62. [PMID: 23066920 DOI: 10.3109/1354750x.2012.730552] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The ratio of the nitric oxide synthase (NOS) cofactor tetrahydrobiopterin (BH(4)) to its oxidized form dihydrobiopterin (BH(2)) has been suggested as an index of endothelial dysfunction. Consequently, much effort has been put into preserving the in vivo equilibrium between these labile analytes. In the present study, we conducted a series of stability experiments in aqueous solutions and blood to identify the most appropriate way of stabilizing BH(4) and BH(2). Based on our results, we are able to recommend that blood samples are immediately stabilized with dithioerythriol and protein precipitation conducted using trichloroacetic acid (TCA).
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Affiliation(s)
- Alan Mortensen
- Faculty of Health and Medical Sciences, Department of Veterinary Disease Biology, University of Copenhagen, Copenhagen, Denmark.
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Czekster CM, Blanchard JS. One substrate, five products: reactions catalyzed by the dihydroneopterin aldolase from Mycobacterium tuberculosis. J Am Chem Soc 2012; 134:19758-71. [PMID: 23150985 DOI: 10.1021/ja308350f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Tetrahydrofolate cofactors are required for one carbon transfer reaction involved in the synthesis of purines, amino acids, and thymidine. Inhibition of tetrahydrofolate biosynthesis is a powerful therapeutic strategy in the treatment of several diseases, and the possibility of using antifolates to inhibit enzymes from Mycobacterium tuberculosis has been explored. This work focuses on the study of the first enzyme in tetrahydrofolate biosynthesis that is unique to bacteria, dihydroneopterin aldolase (MtDHNA). This enzyme requires no metals or cofactors and does not form a protein-mediated Schiff base with the substrate, unlike most aldolases. Here, we were able to demonstrate that the reaction catalyzed by MtDHNA generates three different pterin products, one of which is not produced by other wild-type DHNAs. The enzyme-substrate complex partitions 51% in the first turnover to form the aldolase products, 24% to the epimerase product and 25% to the oxygenase products. The aldolase reaction is strongly pH dependent, and apparent pK(a) values were obtained for the first time for this class of enzyme. Furthermore, chemistry is rate limiting for the aldolase reaction, and the analysis of solvent kinetic isotope effects in steady-state and pre-steady-state conditions, combined with proton inventory studies, revealed that two protons and a likely solvent contribution are involved in formation and breakage of a common intermediate. This study provides information about the plasticity required from a catalyst that possesses high substrate specificity while being capable of utilizing two distinct epimers with the same efficiency to generate five distinct products.
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Affiliation(s)
- Clarissa M Czekster
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
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