Article

SPIN RESONANCE STUDY OF SEROTONIN-FMN INTERACTION

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Part of Szent-Gyorgyi's early work in "quantum biology," this study used electron spin resonance (ESR) technique to investigate charge transfer in biological complexes such as serotonin and flavin mononucleotide (FMN). He found that serotonin and FMN analyzed separately gave no ESR signal (thus indicating that no free radicals had been formed) but when combined, in an acid, they did.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

Book
Full-text available
Szent-Györgyi Albert (1893–1986) neve sokaknak ismerős, mint biokémikus kutató, a C-vitamin feltalálója; máig az egyetlen olyan tudós, aki hazai kutatásáért kapott természettudományos Nobel-díjat. Kevesen ismerik azonban azt az énjét, mely szintén nagy hatással volt a társadalomra. Személyisége, nézetei, gondolkodásmódja és közéleti szerepvállalása mind a mai napig értéket jelentenek a fiatalok és az idősek számára egyaránt. A Kodolányi János Egyetem, fennállása óta (1992-ben főiskolaként alapították), hű névadójához. Kitűnik globális és lokális problémák iránti érzékenysége, amely tettekben is megnyilvánul. Társadalmi szerepvállalása, tettrekészsége, rugalmassága alkalmassá tette arra, hogy térségi folyamatok facilitátoraként, segítőjeként is megjelenjen. Így történt, hogy 2004-ben alapította az egyetem (akkor még főiskolaként) az Orosházi Oktatási Központot, majd székhelyi központját is áthelyezte 2017. február 1-jén. Szent-Györgyi Albert hagyatékához (örökségéhez) hasonlóan, a Kodolányi János Egyetem is jelentős oktatás- és térségszervező erővel bír, és azt a sokszínűséget, melyet az egyetem képvisel, úgy vélem, olvashatják a tudós életútját kutató pedagógusok, érdeklődők is.
Article
The literature data on the donor-acceptor interaction of indoles with various types of electron acceptors used for the explanation of the molecular mechanisms of biochemical processes are examined. The results of research by the authors on the synthesis of polymeric charge-transfer complexes based on 1-vinylindole, halogens, hydrogen halides, alkyl halides, halohydrins, chloranil, and organic derivatives of silicon and tin are correlated.
Article
Serotonin, a good electron donor, was found to have little or no effect on the proboscis of Phascolosoma. The preparation, however, could be sensitized to serotonin by prior application of electron acceptors (sevron blue, acridine red or riboflavin).Similarly, acceptors (naphthoquinone or iodine) sensitized striated muscle to a donor (iodide), producing contracture.It is suggested that electron-transfer reactions could be involved in the contractile responses.
Article
Addition of H2O2 to a bacterial luciferase preparation resulted in the formation of a compound with a fluoresence maximum at about 470 mμ. This compond was probably the same as the one that is formed as a result of ultraviolet irradiation of luciferase preparations after addition of FMNH2. It is assumed to be the luminescent molecule in bacterial luminescence. The effect of a number of substances (K3Fe(CN)6, K4Fe(CN)6, ascorbic acid, peroxidase (donor: H2O2 oxidoreductase, EC 1.11.1.7), tryptophan and p-chloromecuribenzoate) on both the light reaction and fluorescence increase reaction was investigated. Substances inhibiting the fluorescence increase reaction (K3Fe(CN)6, K4Fe(CN)6, ascorbic acid) likewise could inhibit the light reaction. Both effects are, at least partly, ascribed to an effect on the fluorescent group of luciferase. Light reaction inhibitors affecting other groups at the enzyme surface (p-chloromercuribenzoate) did not influence the fluorescence increase effect. Activators of the light reaction (cystine, K4Fe(CN)6) are suggested to act by their protective action on sulfhydryl groups or on dissociable groups, presumed to be attached to these sulfhydryl groups. A discussion of the results leads to the conclusion that the light reaction consists of at least two consecutive reactions, involving two different groups of the luciferase molecule.
Article
Full-text available
Article
Riboflavin-5'-phosphate forms a charge transfer complex with rutin at neutral pH in the same manner as it forms one with tryptophan or serotonin, when the system is observed by quantitative spectrophotometry.
Article
A soluble cell-free system from Thiobacillus neapolitanus is described which catalyzed the oxidation of elemental sulfur to sulfate with a contamitant uptake of oxygen. The preparation did not require the addition of reduced glutathione (GSH) for its activity and, under certain conditions, GSH and other sulfhydryl compounds exerted inhibitory effects. Thiol-binding reagents inhibited sulfur oxidation indicating an involvement of free sulfhydryl groups. The participation of a heavy-metal pathway of electron transport to oxygen was suggested by the inhibitory effect of NaN3 (i mM). KCN, depending on the conditions of the experiment, either inhibited or stimulated oxygen uptake; these effects are discussed and the properties of this preparation are compared with those of sulfur-oxidizing systems isolated from other thiobacilli.
Article
The crystal structure of the red picric acid salt of serotonin was determined by x-ray diffraction methods. The structure consists of parallel hydroxyindole and picrate planes which are intimately stacked with an interplanar separation of 3.3 to 3.4 angstroms. The stacking interaction appears to be of the donor-acceptor (charge-transfer) type, involving specific contacts between picrate nitro groups and atoms of the hydroxyindole moieties. Similar interactions might mediate biological processes involving serotonin.
Article
3,5-Dinitrobenzoate ion has been shown to form a complex in aqueous solution with N-(indole-3-acryloyl)imidazole, p-nitrophenyl 3-indoleacrylate, and p-nitrophenyl 3-indoleacetate. The association constant for the first complex was determined both spectrophotometrically and kinetically, while the association constants of the other two complexes were only determined kinetically. Kinetic analysis indicates that, when complexed with 3,5-dinitrobenzoate ion, all three substrates are unreactive to hydroxide ion, or more specifically react with hydroxide ion less than 3% as fast as the uncomplexed substrate. The lack of reactivity of the complex between N-(indole-3-acryloyl)imidazole and 3,5-dinitrobenzoate ion is probably not due to electrostatic repulsion of the hydroxide ion by the carboxylate ion of the complexing agent, because the complex is also inert to reaction with the neutral nucleophile, n-butylamine. The inhibition of the hydrolysis of N-(indole-3-acryloyl)imidazole can not be attributed to steric effects due to complexation with the imidazole portion of the substrate since p-nitrophenyl 3-indole-acrylate is likewise inhibited and possesses a similar association constant. The results are rationalized in terms of the relative stabilization of the ground and transition states due to complexation.
Article
Macroscopic enantiomerically pure helical supramolecular fibers are bottom‐up assembled in aqueous media from a chiral ‐electron donor template and an achiral ‐electron acceptor. The helices can be assembled to the sub‐millimeter scale with controlled handedness. These dynamic supramolecular architectures allow for a quantitative exchange of the chiral donor template with achiral analogues. During this process, a chiral memory effect was observed, affording enantiomerically pure helices composed entirely of achiral components.
Article
INDOLE and iodine form a black complex that exhibits a strong electron spin resonance signal1. The interpretation that has been given is that indole, if complexed with a small acceptor such as iodine, may act as an especially strong electron donor due to the negative formal charge that exists on carbon 2 and 3.
Article
The unresolved second derivative functions of a number of symmetrical doublets of Lorentzian and Gaussian form have been examined.It has been found that the shape parameter []−min/[]+max can provide means of detecting doublet structure in otherwise unresolvable spectral functions.For the ideal spectral curve forms studied, the parameter can actually provide a measure of the degree of separation involved, which can be considerably beyond the limits of resolution of fine structure obtainable in the second derivative functions.
Article
Electronic structure and reaction procedure of the antimetabolites of folic acid The most important antimetabolites of folic acid, e.g. aminopterine which is utilized in cancer chemotherapy, prevent the transformation of folic acid into tetrahydrofolic acid which is the active form of the coenzyme. These antimetabolites manifest a strong affinity for reductases utilizing pyridine nucleotides as coenzymes, which catalyse this transformation and are resistant to reduction. Molecular orbital calculations indicate that the most basic nitrogen of the antimetabolites is N1 of the folic skeleton, while in the natural substrates it is N8 or N5. They also show that the NH2 group fixed at C2 and the N1 of the antimetabolites are more basic than the same atoms of the natural substrates. In the hypothesis that these two structural elements play a role in the binding between the enzyme and the substrates, this result explains the relatively great affinity of the antimetabolites for the reductases utilizing the pyridine nucleotides as coenzymes. The study of the susceptibility of the available carbons of the cations of the natural substrates and the antmetabolites towards the fixation of H- ions accounts for the resistance of the antimetabolites to reduction. The same resistance appears upon the study of the electron acceptor properties of these molecules.
The formation of molecular complexes between flavine adenine dinucleotide (FAD) and some β-carboline derivatives [antidepressant drugs that have a pronounced inhibition of monoamine oxidase (MAO)] has been studied by using electronic absorption and fluorescence spectroscopic methods. Thermodynamic parameters have been determined from the values of association constants for the molecular complexes at various temperatures. The influence of substituents in the β-carboline molecule on the stability of the complexes formed was also investigated.
The formation of complexes between two flavins [flavine adenine dinucleotide (FAD) and riboflavin (RFN)] and some indole derivatives has been studied in aqueous solution. The molecular associations have been examined by means of electronic absorption spectra, since in each, a new charge-transfer like band has been located, and also by observing the variation of the fluorescence emission of FAD or RFN on the solutions. The formation constants for the molecular complexes were determined from data of absorption using the Foster—Hammick—Wardley method. The quenching fluorescence phenomena observed for the FAD and RFN were related to the concentration of the indole derivatives and the corresponding quenching constants have been determined. Thermodynamic parameters have been derived from the values of association constants for the molecular complexes at several temperatures. Clear evidence is found for the influence on the stability of these complexes of the different substituent groups in the indole derivatives and the molecular structure of both flavins.
Article
An important concern in dealing with complexes is the matter of stability or trends in stabilities. The free energy of complex formation is not intimately related to parameters such as ionization potential, electron affinity, or charge-transfer transition energy. The reasons are several. First, a considerable contribution to the enthalpy part of the free-energy term is from Van der Waals or other forces. It is not expected that these forces will be related in any simple way to those parameters. The entropy contribution to the free energy probably strongly reflects solvation differences and again, no simple correlations are anticipated. The charge-transfer band is always broad, frequently asymmetric, and devoid of vibrational fine structure, even at low temperatures. The broadness and lack of fine structure are undoubtedly due to small variations in the equilibrium distance between partners. Because of the broad and asymmetric character of the charge-transfer absorption, it may often be difficult to determine the position of the absorption maximum precisely.
Chapter
Summary This document is part of Volume 1 ‘Magnetic Properties of Free Radicals’ of Landolt-Börnstein - Group II Molecules and Radicals.
Article
The bulk solution properties of amphiphilic formulations are derivative of their self-assembly into higher ordered supramolecular assemblies known as micelles and of their ordering at the air-water interface. Exerting control over the surface-active properties of amphiphiles and their propensity to aggregate in pure water is most often fine-tuned by covalent modification of their molecular structure. Nevertheless structural constraints which limit the performance of amphiphiles do emerge when trying to develop more sophisticated systems which undergo for example, shape-defined controlled assembly and/or respond to external stimuli. In this regard, the template-modulated assembly of the so-called “supramolecular amphiphiles” continues to make progress ordering molecules that otherwise have very little to no driving force to aggregate in a prescribed manner in aqueous solutions. Herein we describe the template-modulated micellization and ordering at the air-water interface of bipyridinium-based supramolecular amphiphiles triggered by host-guest interactions with high specificity for the neurotransmitter melatonin over its biosynthetic synthon L-tryptophan and the thermodynamic parameters governing the template-modulated micellization process. When bound to the bipyridinium units of micellized surfactant molecules, melatonin effectively serves as “molecular glue” capable of lowering the CMC by 52% as compared to untemplated solutions. Analysis of this system suggests that a hallmark of donor-acceptor template-modulated micellization in water is a strong positively correlated temperature dependence of the CMC and the absence of a U-shaped CMC-temperature curve. Our findings make a case for the incorporation of L-tryptophan-based metabolites and their classical synthetic pharmaceutical bioisosteres as potential targets/components of donor-acceptor charge transfer-based supramolecular amphiphile systems/materials operating in water.
Article
Résumé Le spectre d'absorption, les caractéristiques luminescentes et photochimiques de la riboflavine sont présentés. L'interprétation des données expérimentales d'autres auteurs sur la décomposition photochimique de l'eau sensibilisée par la riboflavine est critiquée. Il faut distinguer deux cas: dans les réactions photochimiques qui ont lieu en l'absence de donneurs d'électrons ajoutés, la portion ribosique de la riboflavine se comporte en donneuse d'électrons et elle est détruité. Par contre, en présence de donneurs d'électrons adjoutés, la riboflavine agit comme véritable photosensibilisateur et n'est pas consumée dans l'ensemble de la réaction photochimique.
Article
The problems experienced by “normal” adolescents are described and some indication given of the range and seriousness of problems from the adolescent viewpoint. Seven hundred and seventy-five 15-year-olds from comprehensive schools in the North of England completed two questionnaires and a sub-sample of these adolescents were interviewed in detail about their problem experiences, who they confided in and what they thought could be done about problems.The most common worries for the adolescents were concerned with Employment, Self-Confidence and Adequacy and the Academic aspects of School. Least mentioned problems were in the areas of Material Deprivation, Physical Inadequacy and Home. The latter problems however affect a minority of adolescents (10–30 per cent) and appeared more difficult for them to solve. Peer acceptance was an area of worry which affected a considerable number, but problems regarding authority and control, etc. were less prevalent.
Article
A method for extracting aflatoxin M1 from milk is proposed in which the use of disposable Extrelut clean-up columns simplifies the analysis considerably in comparison with existing methods. The quantitative determination is based on one-dimensional thin-layer chromatography and fluorescence densitometric measurement. The detection limit is 5 ppt (parts per 10(12)) in milk and the recovery is 78 +/- 4% at a level of 50 ppt.