Rui Fontes

Universidade do Porto

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i-10 index

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Co-Authors

Joaquim C. G. Esteves da Silva

Universidade do Porto

Hugo Fraga

Institut de Biologie Structurale

A Sillero

Universidad Autónoma de Madrid

João Meireles Ribeiro

Universidad de Extremadura

Marı́a A. Günther Sillero

Instituto de Investigaciones Biomédicas Sols-Morreale

Antonio Sillero

Universidad Autónoma de Madrid

Diogo Fernandes

Universidade do Porto

Begoña Ortiz

Universidad Autónoma de Madrid

Abel J. Duarte

Rede de Química e Tecnologia

Anabel de Diego

Instituto de Investigaciones Biomédicas Sols-Morreale

Cooperative Institutions

Universidade do Porto

Universidad Autónoma de Madrid

Consejo Superior de Investigaciones Científicas

Rede de Química e Tecnologia

Hospital de São João

Instituto de Investigaciones Biomédicas Sols-Morreale

i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto

Universidad de Extremadura

Instituto Superior de Engenharia do Porto

Centro de Investigaciones Biológicas Margarita Salas

Author Statistics

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Firefly Luciferase Produces Hydrogen Peroxide as a Coproduct in Dehydroluciferyl Adenylate Formation

ChemBioChem (2006)

Hugo Fraga Diogo Fernandes J. Novotný Rui Fontes Joaquim C. G. Esteves da Silva

Abstract Firefly luciferase catalyzes the synthesis of H 2 O 2 from the same substrates as the bioluminescence reaction: ATP and luciferin ( d‐ LH 2 ). About 80 % of the enzyme‐bound intermediate d‐ luciferyl adenylate ( d‐ LH 2 ‐AMP) is oxidized into oxyluciferin, and a photon is emitted during this reaction. The enzyme pathway responsible for the generation of H 2 O 2 is a side reaction in which d‐ LH 2 ‐AMP is oxidized into dehydroluciferyl adenylate ( L‐AMP ). Like the bioluminescence reaction, the luciferase‐catalyzed synthesis of H 2 O 2 and L‐AMP is a stereospecific process, involving only the natural D enantiomer. However, the intramolecular electron transfer postulated as essential to the light emission process is not involved in this side reaction.

Luciferin

Stereospecificity

Luciferases

Enantiomeric excess

10.1002/cbic.200500443

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Citations (59)

Pyrophosphate and tripolyphosphate affect firefly luciferase luminescence because they act as substrates and not as allosteric effectors

FEBS Journal (2008)

Rui Fontes Diogo Fernandes Filipe Peralta Hugo Fraga Inês Maio

The activating and stabilizing effects of inorganic pyrophosphate, tripolyphosphate and nucleoside triphosphates on firefly luciferase bioluminescence were studied. The results obtained show that those effects are a consequence of the luciferase‐catalyzed splitting of dehydroluciferyl‐adenylate, a powerful inhibitor formed as a side product in the course of the bioluminescence reaction. Inorganic pyrophosphate, tripolyphosphate, CTP and UTP antagonize the inhibitory effect of dehydroluciferyl‐adenylate because they react with it giving rise to products that are, at least, less powerful inhibitors. Moreover, we demonstrate that the antagonizing effects depended on the rate of the splitting reactions being higher in the cases of inorganic pyrophosphate and tripolyphosphate and lower in the cases of CTP and UTP. In the case of inorganic pyrophosphate, the correlation between the rate of dehydroluciferyl‐adenylate pyrophosphorolysis and the activating effect on bioluminescence only occurs for low concentrations because inorganic pyrophosphate is, simultaneously, an inhibitor of the bioluminescence reaction. Our results demonstrate that previous reports concerning the activating effects of several nucleotides (including some that do not react with dehydroluciferyl‐adenylate) on bioluminescence were caused by the presence of inorganic pyrophosphate contamination in the preparations used.

10.1111/j.1742-4658.2008.06309.x

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Citations (39)

Chemical synthesis and firefly luciferase produced dehydroluciferyl-coenzyme A

Tetrahedron Letters (2004)

Hugo Fraga Joaquim C. G. Esteves da Silva Rui Fontes

Coenzyme A

10.1016/j.tetlet.2004.01.050

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Citations (13)

Enzyme inhibition as visualized with the reservoir model: Relationships between i50 and inhibition constant(s) of an enzyme inhibitor

Computers in Biology and Medicine (1994)

João Meireles Ribeiro Rui Fontes Antonio Sillero

Enzyme Inhibition

Constant (computer programming)

Soil enzyme

Enzyme Kinetics

10.1016/0010-4825(94)90071-x

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Citations (6)

An easy procedure to transform the ratio of two polynomials of first degree into Michaelis-Menten-type equations. Application to the ordered Uni Bi enzyme mechanism.

Acta Biochimica Polonica (2000)

Rui Fontes João Meireles Ribeiro A Sillero

It is not always clear that some equations affected by complicated factors can, actually, be interpreted as a ratio of two polynomials of first degree and so that they can be, in general, represented by rectangular hyperbolas. In this paper we present an easy procedure to rearrange those equations into Michaelis-Menten-type equations and so to make the aspects of these rectangular hyperbolas more clear, particularly for researchers familiar with general biochemistry. As an example, the method is applied to transform the classical rate equation of the Cleland's Ordered Uni Bi enzyme mechanism.

Hyperbola

Michaelis–Menten kinetics

Degree (music)

Rate equation

10.18388/abp.2000_4083

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Citations (3)

Turn-on, photostable, nontoxic and specific, iron(II) sensor

Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy (2021)

Helena M.R. Gonçalves Isabel S. Tavares Susana A.F. Neves Rui Fontes Abel J. Duarte

Cooperativity

10.1016/j.saa.2021.120380

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Citations (11)

Dehydroluciferyl‐AMP is the main intermediate in the luciferin dependent synthesis of Ap₄A catalyzed by firefly luciferase

FEBS Letters (1998)

Rui Fontes Begoña Ortiz Anabel de Diego Antonio Sillero Marı́a A. Günther Sillero

It was previously assumed that E·LH 2 ‐AMP was the intermediate complex in the synthesis of Ap 4 A catalyzed by firefly luciferase (EC 1.13.12.7), when luciferin (LH 2 ) was used as cofactor. However, here we show that LH 2 is partly transformed, shortly after the onset of the luciferase reaction, to dehydroluciferin (L) with formation of an E·L‐AMP complex which is the main intermediate for the synthesis of Ap 4 A. Formation of three more derivatives of LH 2 were also observed, related to the production of light by the enzyme. CoA, a known stimulator of light production, inhibits the synthesis of Ap 4 A by reacting with the E·L‐AMP complex and yielding L‐CoA.

Luciferin

10.1016/s0014-5793(98)01301-5

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Citations (47)

Reliability Evidence for Examination Cut Scores within a Medical School

Journal of Education and Learning (2012)

Mílton Severo Rita Gaio Daniel Duarte Dantas Moura Rui Fontes Teresa Rodrigues

Establishing credible cut scores for performance-type examinations in health professions education can bechallenging. The authors aimed to compare the pass-fail cut-score reliability with the maximum reliabilitycut-score from multiple-choice tests (MCTs) designed on different undergraduate disciplines. Using thecross-sectional evaluation of 1370 tests from six disciplines from Porto medical school, Portugal, in 2010, thepass-fail cut-score reliability was obtained from the one-parameter logistic model of item response theory model.The test information curve achieved maximum reliability for ability levels ranging from -1.40 to -0.01 standarddeviations below the average. The pass-fail cut score for estimated ability ranged from -1.36 to 0.25. Theseresults showed that all MCTs had a pass and fail threshold of competence, and that was appropriate for themaximum information obtainable from the examination to occur at the pass and fail level; nevertheless, themaximum information was not achieved in the pass and fail level.

10.5539/jel.v1n1p77

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Citations (0)

Synthesis of Luciferyl Coenzyme A: A Bioluminescent Substrate for Firefly Luciferase in the Presence of AMP

Angewandte Chemie International Edition (2005)

Hugo Fraga Rui Fontes Joaquim C. G. Esteves da Silva

Shedding light on luciferase: Luciferyl coenzyme A (1) was synthesized and it was found that luciferase catalyzes light production from luciferyl coenzyme A and AMP. The results of this study open perspectives for new bioanalytical methods and are strong evidence for the evolutionary relationship between firefly luciferase and acyl-CoA synthetases.

Luciferin

Luciferases

Coenzyme A

10.1002/anie.200462934

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Citations (10)

A Tridimensional Representation of Enzyme Inhibition Useful for Diagnostic Purposes

Journal of enzyme inhibition (1994)

Rui Fontes João Meireles Ribeiro A Sillero

AbstractAbstractA new three dimensional representation of enzyme inhibition, applied to Lineweaver-Burk, Hanes and Eadie-Hofstee plots is presented. This type of representation has advantages for enzyme inhibition diagnosis, showing graphic characteristics that pass unnoticed in linear plots.Key Words: : Diagnosis of enzyme inhibitiongraphic techniquesthree dimensional representation

Representation

Enzyme Inhibition

10.3109/14756369409020191

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Citations (8)