Photoinactivation of tyrosinase sensitized by folic acid photoproducts

Dántola, M. Laura; Zurbano, Beatriz N.; Thomas, Andrés H.

doi:10.1016/j.jphotobiol.2015.06.002

Cited by 15 publications

(7 citation statements)

References 53 publications

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“…The activity of TYR decreased significantly when the enzyme was exposed to radiation in the presence of PteGlu [60]. Nevertheless, the comparison of the kinetic profiles of PteGlu photodegradation and TYR photoinactivation indicated that in the first minutes of irradiation, the concentration of PteGlu did not change significantly, whereas no loss of the enzyme activity was registered.…”

Section: Photoinactivation Of Tyrosinasementioning

confidence: 88%

Photosensitization of peptides and proteins by pterin derivatives

et al. 2017

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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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Section: Photoinactivation Of Tyrosinasementioning

confidence: 88%

Photosensitization of peptides and proteins by pterin derivatives

et al. 2017

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“…18 It has been reported that different pterin derivatives are able to photoinduce the inactivation of tyrosinase, an essential enzyme in the melanin biosynthesis. 22 Studies performed with human serum albumin (HSA) revealed that Ptr photosensitizes the oxidation and the oligomerization of HSA. 23 Several amino acids are oxidized in these processes and the oligomerization is mediated by the formation of tyrosine dimers (Tyr2).…”

Section: Introductionmentioning

confidence: 99%

Chemical Modifications of Globular Proteins Phototriggered by an Endogenous Photosensitizer

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Dántola

Petroselli

et al. 2019

Chem. Res. Toxicol.

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The main goal of the present work was to investigate the damages photoinduced by pterin (Ptr), an endogenous photosensitizer present in human skin under pathological conditions, on a globular protein such as ubiquitin (Ub). A particular attention has been paid on the formation of covalent adducts between Ptr and the protein that can behave as photoantigen and provoke an immune system response. Here, a multifaceted approach including UV/visible spectrophotometry, fluorescence spectroscopy, electrophoresis, size exclusion chromatography and mass spectrometry is used to establish the Ub changes triggered by UVA irradiation in the presence of Ptr. Under anaerobic conditions, the only reaction corresponds to the formation of a covalently bound Ptr-Ub adduct that retains the spectroscopic properties of the free photosensitizer. A more complex scheme is observed in air-equilibrated solutions with the occurrence of three different processes ie. formation of a Ptr-Ub adduct, dimerization and fragmentation of the protein. General Chemicals. Pterin (Ptr, purity > 99%, Schircks Laboratories, Switzerland) and ubiquitin from bovine erythrocytes, whose sequence is identical to the human protein, (Sigma-Aldrich, St. Louis, MO) were used without further purification after checking for impurities by HPLC. Sodium dodecyl sulfate (SDS, ~ 99 %), glycerol, 2mercaptoethanol, bromophenol blue, glycine (Gly, > 99% titration), ammonium persulphate (> 98%), N,N,N´,N´-tetramethylethylene-diamine (TEMED, ~ 99 %), Cytochrome c (Cyt) from horse heart, E-3,5-dimethoxy-4-hydroxycinnamic acid (E-SA), α-cyano-4-hydroxycinnamic acid (CHCA), bradykinin (1-7), insulin, angiotensin I and II and guanidine chloride were provided by Sigma Aldrich. Methanol was provided by Laboratorios Cicarelli. Trifluoroacetic acid (TFA) was provided by Merck. Acetic acid was provided by Anedra. Coomassie Brilliant Blue G was provided by Fluka. Acrylamide, N´,N´-methylene-bis-acrylamide and trishydroxymethylaminomethane (Tris) were purchased by Genbiotech. NaCl and acetonitrile were provided by J. T. Baker. Aqueous solutions were prepared using ultrapure water from Milli-Q ® purification system (Millipore Corporation, USA). Measurements of pH. The pH measurements were performed using a pH-meter sensION+ pH31 GLP combined with a pH electrode 5010T (Hach) or microelectrode XC161 (Radiometer Analytical). The pH of the aqueous solutions was adjusted by adding drops of HCl and NaOH solutions from a micropipette. The concentration of the acid and the base used for this purpose ranged from 0.1 to 2 M. UV⁄vis analysis. Electronic absorption spectra were recorded on a Shimadzu UV-1800 spectrophotometer. Measurements were made using quartz cells of 0.4 or 1 cm optical pathlength. The absorption spectra of the solutions were recorded at regular intervals of irradiation time.

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“…Nucleoside analogues have been synthesized as pterin derivatives . In the presence of oxygen, aromatic pterins act as photosensitizers through both type I (generation of radicals via electron transfer or hydrogen abstraction) and type II (production of 1 O 2 ) mechanisms; , the former species (such as hydroxyl radicals) have very short diffusion distances, but the latter species 1 O 2 can diffuse one hundred or more nanometers in biological media. , Pterins are reported to photosensitize oxidation of biomolecules, such as nucleotides, DNA, amino acids, peptides, proteins, , and biomembranes . Relatedly, pterins have been found to induce the photokilling of cervical cancer (HeLa) cells upon UVA irradiation, and alter the integrity of the cell membranes, among other deleterious aspects .…”

Section: Introductionmentioning

confidence: 99%

Lipophilic Decyl Chain–Pterin Conjugates with Sensitizer Properties

et al. 2017

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A new series of decyl chain [-(CH)CH] pterin conjugates have been investigated by photochemical and photophysical methods, and with theoretical solubility calculations. To synthesize the pterins, a nucleophilic substitution (S2) reaction was used for the regioselective coupling of the alkyl chain to the O site over the N site. However, the O-alkylated pterin converts to N-alkylated pterin under basic conditions, pointing to a kinetic product in the former and a thermodynamic product in the latter. Two additional adducts were also obtained from an N-amine condensation of DMF solvent molecule as byproducts. In comparison to the natural product pterin, the alkyl chain pterins possess reduced fluorescence quantum yields (Φ) and increased singlet oxygen quantum yields (Φ). It is shown that the DMF-condensed pterins were more photostable compared to the N- and O-alkylated pterins bearing a free amine group. The alkyl chain pterins efficiently intercalate in large unilamellar vesicles, which is a good indicator of their potential use as photosensitizers in biomembranes. Our study serves as a starting point where the synthesis can be expanded to produce a wider series of lipophilic, photooxidatively active pterins.

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Photoinactivation of tyrosinase sensitized by folic acid photoproducts

Cited by 15 publications

References 53 publications

Photosensitization of peptides and proteins by pterin derivatives

Photosensitization of peptides and proteins by pterin derivatives

Chemical Modifications of Globular Proteins Phototriggered by an Endogenous Photosensitizer

Lipophilic Decyl Chain–Pterin Conjugates with Sensitizer Properties

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