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1.
Klin Lab Diagn ; 63(12): 732-740, 2018.
Artigo em Russo | MEDLINE | ID: mdl-30785686

RESUMO

Somatic cells at the early stages of phylogenesis realized the metabolism of long-chain fatty acids (FA), primarily palmitic saturated FA. It dominated the construction of a bilayer cell membrane and as a substrate for oxidation in mitochondria during energy production. Later, polyene FAs became involved in the construction of the cell membrane, the membranes of intracellular organelles, and became the substrate for the synthesis of biologically active eicosanoids. At later stages of phylogenesis, the metabolism of medium-chain FAs is activated and the formation of ketone bodies as a substrate, which is available for oxidation by the mitochondria of the formed cells of the nervous tissue in the absence of first substrate glucose. In the later stages of phylogenesis, insulin initiated: a) the transformation of carnivorous ancestors of the species Homo sapiens in the ocean into a herbivorous species while living on land; b) the formation of the new biological function of locomotion and c) the dominance of the oleic variant of the metabolism of long-chain fatty acids with higher kinetic parameters of mitochondria oxidation. Metabolites of medium chain FA have become humoral mediators of metabolism and the formation of feedback mechanisms in the function of trophology and cognitive biological function. The formation of an oleic variant of the metabolism of fatty acids under the action of insulin led to the improvement of the energy supply of cells and the high kinetic parameters of many species of herbivorous mammals, including Homo sapiens. The species Homo sapiens was not omnivorous (Omnivores); the insulin's regulatory action during life on land has turned it into a herbivorous species (Herbivore), but with a carnivorous (Carnivore) (fish-eating) past. Seven metabolic pandemics (1. atherosclerosis and atheromatosis; 2. metabolic arterial hypertension; 3. metabolic syndrome; 4. insulin resistance syndrome; 5. obesity; 6. nonalcoholic fatty liver disease and 7. endogenous hyperuricemia) are only functional disorders and can be, in most cases, eliminated. From the standpoint of the phylogenetic theory of general pathology, atherosclerosis and atheromatosis of the arteries have no great future. As soon, as the majority of individuals of the Homo sapiens species realize that in phylogenesis they have formed as herbivores and stop eating excessive amounts of meat food, exogenous palmitic FA, the incidence in the population will begin to decrease. Patients are still obliged to justify the binary, biological name of the species - reasonable man. Prevention and other metabolic pandemics, diseases of civilization, can be discussed. It takes time, an understanding of what happens by the doctors, diligence and the desire of patients to be healthy.


Assuntos
Ácidos Graxos/metabolismo , Insulina/metabolismo , Filogenia , Animais , Aterosclerose , Dieta , Humanos , Resistência à Insulina , Síndrome Metabólica
2.
Klin Lab Diagn ; 60(2): 13-8, 2015 Feb.
Artigo em Russo | MEDLINE | ID: mdl-26027252

RESUMO

The control of cellular metabolism is present in many organs and tissues and its loss means development of hypo- and hyperglycemia. The high level of glucose results in glycation of proteins and increase of concentration of ketoaldehyde and methyl glyoxal in cells. The increase of level of this ketoaldehyde and D-lactate in organs and tissues also can be a result offormation of methyl glyoxal in particular enzymatic reactions including decomposition of one of substrates of glycolysis and conversion of aminoacetone catalyzed by semicarbazide-sensitive amine oxydase of endothelium cells. The methyl glyoxal attacks arginine residuals of proteins. This aldehyde is related to interruption in transmission of insulin signal, disorder of pro-antioxidant balance, inhibition of enzymes of glycolysis, etc. The model of cellular metabolism is proposed where methyl glyoxal plays a key role in development of resistance to insulin, hyperglycemia, hypokalemia and hypertension. The modes of increase of consumption of glucose in conditions of low activity of protein tyrosine kinase are considered. The possible involvement of tokopherol (its derivatives) in activation ofphosphodiesterase in liver and regulation of carbohydrate metabolism is considered too. The role of tokopherol-carrier proteins and effect of tokopherol on functioning of OI-cells is discussed. It is still unclear if there is a direct relationship between low level of tokopherol-carrier proteins and diabetes or hypertension. Howeve, low level of tokopherol-carrier proteins results in "prolonged oxidative stress".


Assuntos
Diabetes Mellitus Tipo 2/metabolismo , Hiperglicemia/metabolismo , Hipertensão/metabolismo , Estresse Oxidativo , Aldeídos/metabolismo , Antioxidantes/metabolismo , Diabetes Mellitus Tipo 2/etiologia , Diabetes Mellitus Tipo 2/fisiopatologia , Glucose/metabolismo , Produtos Finais de Glicação Avançada/metabolismo , Glioxal/metabolismo , Humanos , Hiperglicemia/fisiopatologia , Hipertensão/etiologia , Hipertensão/fisiopatologia , Insulina/metabolismo
3.
Bull Exp Biol Med ; 156(2): 191-5, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24319746

RESUMO

The existence of lipid-radical cycles in membranes as an LPO alternative has been proven. Cytochrome b5 seems to play the key role in the formation of these cycles. The functional role of lipid-radical cycles in cell metabolism, including the positive effect on microsomal and mitochondrial oxidation, is discussed.


Assuntos
Proteínas de Transporte/metabolismo , Hemeproteínas/metabolismo , Fígado/metabolismo , Microssomos Hepáticos/metabolismo , Mitocôndrias/metabolismo , alfa-Tocoferol/farmacologia , Trifosfato de Adenosina/biossíntese , Trifosfato de Adenosina/química , Envelhecimento , Animais , Antioxidantes/farmacologia , Derivados de Benzeno/farmacologia , Membrana Celular/metabolismo , Proteínas Ligantes de Grupo Heme , Metabolismo dos Lipídeos , Peroxidação de Lipídeos/fisiologia , Fígado/citologia , Masculino , NAD/química , Oxirredução , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio
5.
Cell Biochem Biophys ; 59(3): 133-46, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21104158

RESUMO

In 1961, Peter Mitchell advanced a new idea for solving the problem of coupling between oxidation and phosphorylation, but some aspects of the relationship between the redox-chain as a potential energy donor and different energy acceptors remain largely unknown. The main structure-function relationships behind catalytic rate optimization in membrane enzymes are highly important, and comparative analyses of the energetics of catalytic reactions from membrane proteins of different destination are needed to advance our understanding. Moreover, the mode of control of primary radicals, such as reactive oxygen species (ROS), should be considered. For example, iron is essential for most organisms because it serves as an electron donor and acceptor in various metabolic processes. However, these chemical properties also allow iron to participate in the formation of ROS that cause substantial damage to lipids; iron can contribute to excess production of damaging ROS through Fenton chemistry. The evidence that iron contributes to various diseases of ageing is to be examined along with the need for low or moderate levels of iron, depending on homeostasis level. If this level in the organs and tissues is close to the optimal amount needed for an initiation of lipid-radical cycles, which may be responsible for the effectiveness of some membrane enzymes, this might minimize the ROS production and retard the processes related to ageing. To my mind, biological membranes possess an internal heat and imaginary temperature that are new, unique physiological parameters related to a role as factors of biological catalysis. This is speculation and additional studies will be needed to determine whether the imaginary temperature has an equal importance with the real temperature in cellular metabolism, membrane energetics (microsomal monooxygenase and ATP synthesis) and ageing.


Assuntos
Biocatálise , Membrana Celular/metabolismo , Temperatura Alta , Nanoestruturas/química , Animais , Membrana Celular/química , Membrana Celular/enzimologia , Humanos
6.
Klin Lab Diagn ; (3): 22-36, 2010 Mar.
Artigo em Russo | MEDLINE | ID: mdl-20737676

RESUMO

In philogenesis, due to the failure to store a great deal of carbohydrates in vivo as glycogen, all animal species began synthesizing from glucose palminitic fatty acid and depositing it as triglycerides. During biological dysfunction of exotrophy (long starvation, early postnatality, hibernation), cells also accomplish a reverse synthesis of glucose from fatty acids under aerobic conditions. Under physiological conditions, acetyl-CoA that is converted to malate and pyruvate in the glyoxalate cycle is a substrate of glyconeogenesis. Under pathological conditions of hypoxia and deficiency of macroerges, gluconeogenesis occurs without ATP consumption through the methylglyoxal pathway when used as a substrate of ketone bodies via the pathway: butyric acid (butyrate) --> beta-hydroxybutyrate --> acetoacetate --> acetone --> acetol --> methylglyoxal --> S-D-lactol-glutathione --> D-lactate --> pyruvate --> D-lactate. Under physiological conditions, this gluconeogenesis pathway does not function. We believe that with low glucose levels in the cell cytosole (glycopenia), under pathological conditions of hypoxia and due to failure to mitochondria to oxidize fatty acids, gene expression and gluconeogenesis occur through the methylglyoxal pathway. At the same time, the cytosol, intercellular environment, and plasma shows the elevated levels of methylglyoxal and D-lactate that it is converted to by the action of glyoxalases I and II. Under pathological conditions, glycopenia develops in starvation, diabetes, and metabolic acidosis, neoplasms, renal failure, and possibly, metabolic syndrome. The chemical interaction of methylglyoxal with the amino acid residues of lysine and arginine results in the denaturation of circulating and structurized proteins via carbonylation--glycosylation.


Assuntos
Citosol/metabolismo , Ácidos Graxos/metabolismo , Glucose/biossíntese , Aldeído Pirúvico/metabolismo , Animais , Diabetes Mellitus/diagnóstico , Diabetes Mellitus/metabolismo , Cetoacidose Diabética/diagnóstico , Cetoacidose Diabética/metabolismo , Metabolismo Energético , Gluconeogênese , Humanos , Corpos Cetônicos/metabolismo , Ácido Láctico/metabolismo , Neoplasias/diagnóstico , Neoplasias/metabolismo , Desnaturação de Ácido Nucleico , Desnaturação Proteica , Aldeído Pirúvico/análise , Insuficiência Renal/diagnóstico , Insuficiência Renal/metabolismo
7.
Ter Arkh ; 82(10): 71-7, 2010.
Artigo em Russo | MEDLINE | ID: mdl-21341469

RESUMO

If a lot of carbohydrates cannot be in vivo stored as glycogen, the synthesis of palmitic fatty acid (FA) from glucose and its adipocyte deposition as triglycerides are under way in phylogenesis. With impaired biological function of exotrophy (fasting, early postnatality, hibernation), the cells perform a reverse process--the synthesis of glucose from FA. Physiologically, the substrate of gluconeogenesis is acetyl-CoA that is converted by the malate --> 9 piruvate --> glucose pathway in the glyoxalate cycle. Under the pathological conditions of hypoxia and energy deficiency, gluconeogenesis occurs without ATP consumption via the methylglyoxalate pathway (MGP) while using as a substrate of ketone bodies: butyric acid (butyrate) --> beta-hydroxybutyrate --> acetoacetate --> acetone --> acetol --> methylglyoxal (MG) --> S-D-lactolglutathione --> D-lactate --> piruvate --> D-lactate. Under physiological conditions, this pathway of gluconeogenesis does not work. The authors hold that gene expression and gluconeogenesis occur via the MGP when glucose levels are low in the cell cytosol (glycopenia) and FA cannot be oxidized in the mitochondria. Cytosol, intercellular medium, plasma show elevated levels of MG and D-lactate, to which it converts under the action of glyoxalases I and II. Glycopenia develops in fasting, diabetes mellitus, metabolic syndrome, renal failure, phenofibrate therapy, impaired function of exotrophy--excessive dietary intake of saturated and trans fatty acids. The chemical interaction of MG with amino acid residues of lysine and arginine leads to protein denaturation during carbonylation--glycosylation and impaired biological function of endoecology. The determination of plasma MG and D-lactate may be a test for glycopenia, compensatory activation of gluconeogenesis from FA or for the evaluation of endogenous intoxication.


Assuntos
Citosol/metabolismo , Ácidos Graxos/metabolismo , Gluconeogênese , Glucose/biossíntese , Homeostase , Aldeído Pirúvico/análise , Animais , Gluconeogênese/fisiologia , Homeostase/fisiologia , Humanos , Aldeído Pirúvico/metabolismo
8.
Ageing Res Rev ; 9(2): 200-10, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19800421

RESUMO

Lipid intermediates which are generated by ROS have drawn more attention after it was found that lipid peroxidation and lipid-radical cycles are two alternative processes. In biological membranes alpha-tocopherol and cytochrome b5, as known, act synergistically to overcome free radical injury and to form lipid-radical cycles. These cycles activate membrane proteins, protect membrane lipids from oxidation and prevent from formation of endogenous aldehydes. Experimental and clinical evidence accumulated for 5-6 years suggests that endogenous aldehydes, such as malonic dialdehyde (MDA) and methylglyoxal (MG), are the major initiators of the metabolic disorders. The age-related diseases emerge when cells cannot control formation of aldehydes and/or cannot abolish the negative effect of methylglyoxal on their metabolism. If the efficiency of the glyoxalase system is insufficient toxic aldehydes cause cumulative damage over a lifetime. In this paper, we provide evidence to consider ageing as a process in which lipid-radical cycles gradually substitute for lipid peroxidation. There are always two opposing tendencies or actions which counteract each other - actions of melatonin, lipid-radical cycles and the glyoxalase system (anti-ageing effect) and negative actions of the toxic aldehydes (pro-ageing effect). Life span is determined by the balance of two opposing processes.


Assuntos
Envelhecimento/metabolismo , Aldeídos/metabolismo , Radicais Livres/metabolismo , Lactoilglutationa Liase/metabolismo , Peroxidação de Lipídeos/fisiologia , Estresse Oxidativo/fisiologia , Envelhecimento/patologia , Humanos , Metabolismo dos Lipídeos/fisiologia , Doenças Metabólicas/metabolismo , Doenças Metabólicas/fisiopatologia , Aldeído Pirúvico/metabolismo
9.
Arch Physiol Biochem ; 113(2): 87-95, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-17558607

RESUMO

There are many well-documented errors of metabolism involving genetic defects that affect carbohydrate utilization. The array of disorders includes the defective utilization of glucose, as well as enzymatic deficiencies in glycolysis and gluconeogenesis, and the pentose phosphate pathway. Besides, there is considerable literature about metabolic syndrome and diabetes. However, the main problem of their origin remains obscure. Also, it is presently beyond doubt that there are various causes of insulin resistance. The development of insulin resistance may be associated not only with insulin production disorders or presence of insulin antagonists but also with modification of the number of receptors and sensitivity of peripheral tissues. The insulin resistance originates from insulin signal transmission defects at its initial stages. It is presently uncertain which mechanisms of adaptation regulation are activated or should be activated under hyperglycemia conditions. This is the main problem of the selection of strategy of hyperglycemia treatment but it is important that aldehydes - the secondary products of lipid peroxidation and protein glycation (malondialdehyde and methylglyoxal) - make a contribution to abnormal metabolism. As far as the role of methylglyoxal in inhibition of antioxidant enzymes is concerned, the involvement of the ketoaldehyde in such processes as oxidative stress, cell proliferation control, and carbohydrate metabolism disorders does not cast any doubt.


Assuntos
Aldeídos/metabolismo , Metabolismo dos Carboidratos , Animais , Humanos , Hiperglicemia/metabolismo , Insulina/fisiologia
10.
J Alzheimers Dis ; 11(2): 183-90, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17522443

RESUMO

The major cause of neurodegenerative disorders, including mid- to late-life onset Alzheimer's Disease, is permanent oxidative stress in the brain. Polyunsaturated fatty acids (PUFA) and alpha-tocopherol (alpha-TOH) are the most oxygen-sensitive constituents of cells. The presence of alpha-TOH in biological membranes is required but not sufficient to protect them against lipid peroxidation. The data presented in this review consider the role of alpha-TOH and cytochrome b5 which permit operation of lipid-radical cycles and the participation of lipid-radical reactions in key processes occurring in the membrane. Analysis of role of these cycles in membrane bioenergetics led us to a model involving the adenine nucleotide translocator and ATP synthesis in brain mitochondria. This paper summarizes experimental evidence for oxidative and non-oxidative pathways of PUFA metabolism with respective intermediates, which could be relevant to elucidation of new mechanisms of neurodegenerative diseases. Lipid-radical reactions in membranes work as important component of normal cell metabolism. Discussion is focused on the consequences of ineffective electron transfer to peroxyl radicals (LOO.--> LOO-) and excessive oxidative pathway of PUFA metabolism (LOO.-->LOOH) with two reactive secondary products: malondialdehyde and methylglyoxal. Our future aim is to develop a more detailed model supplemented by the formation of lipofuscin and amyloid structures.


Assuntos
Doença de Alzheimer/fisiopatologia , Radicais Livres/metabolismo , Peroxidação de Lipídeos/fisiologia , Translocador 1 do Nucleotídeo Adenina/fisiologia , Trifosfato de Adenosina/metabolismo , Animais , Encéfalo/fisiopatologia , Citocromos b5/fisiologia , Ácidos Graxos Insaturados/metabolismo , Humanos , Mitocôndrias/fisiologia , Membranas Mitocondriais/fisiologia , Aldeído Pirúvico , alfa-Tocoferol/metabolismo
11.
Mol Cell Biochem ; 289(1-2): 49-53, 2006 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16583131

RESUMO

Malondialdehyde (MDA) is one of cytotoxic aldehydes produced in cells as a result of lipid peroxidation and further MDA metabolism in cytoplasm is not known. In our experiments the liver fraction 10,000 g containing phosphoglucose isomerase and enzymes of the glyoxalase system was used and obtained experimental data shows that in this fraction there is an aggregate of reactions taking place both in membranes (lipid peroxidation) and outside membranes. MDA accumulation is relatively slow because MDA is a substrate of aldehyde isomerase (MDA <--> methylglyoxal). The well known enzyme phosphoglucose isomerase acts as an aldehyde isomerase (Michaelis constant for this enzyme Km = 133 +/- 8 microM). MDA conversion to methylglyoxal and further to neutral product D-lactate (with GSH as a cofactor) occurs in cytoplasm and D-lactate should be regarded as the end product of two different parametabolic reactions: lipid peroxidation or protein glycation.


Assuntos
Ácido Ascórbico/farmacologia , Derivados de Benzeno/farmacologia , Compostos Ferrosos/farmacologia , Glucose-6-Fosfato Isomerase/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Peróxidos/farmacologia , Animais , Cinética , Ácido Láctico/metabolismo , Fígado/metabolismo , Malondialdeído/química , Malondialdeído/metabolismo , Ratos , Ratos Wistar
12.
Biochemistry (Mosc) ; 70(11): 1251-5, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16336185

RESUMO

Lipid peroxidation in biological membranes is accompanied by malonic dialdehyde (MDA) formation, but the problem of its further metabolism in cytoplasm remains unsolved. The experimental data obtained in this work showed that the liver fraction prepared by centrifugation at 10,000g contained phosphoglucose isomerase and enzymes of the glyoxalase system. In this fraction in the presence of GSH there is an aggregate of reactions taking place both in membranes (lipid peroxidation) and outside membranes (MDA conversion to methylglyoxal and further to neutral D-lactate). This means that MDA is slowly accumulated because it is a substrate of aldehyde isomerase (MDA <--> methylglyoxal). Most probably, phosphoglucose isomerase serves as this enzyme. We concluded that D-lactate should be regarded as the end product of two different parametabolic reactions: lipid peroxidation or protein glycation.


Assuntos
Aldeídos/metabolismo , Glucose-6-Fosfato Isomerase/metabolismo , Animais , Glicólise , Peroxidação de Lipídeos , Fígado/enzimologia , Malondialdeído/metabolismo , Ratos , Ratos Wistar
15.
Biofizika ; 48(3): 417-25, 2003.
Artigo em Russo | MEDLINE | ID: mdl-12815851

RESUMO

A hypothesis of enzymic catalysis was put forward according to which the energy of the exothermic reaction that takes place in aqueous medium is used for a shift of equilibrium in the endothermic reaction, a reaction involving hydrated ions. This occurs in accordance with the Le Chatelier's principle, and, as a result of water dissociation in a homogeneous medium, a gradient of H+ and OH- ions is generated at the water/protein interface. It follows from the hypothesis that the chemical conversion of the substrate to the product is preceded by the attack of hydrated ions on the protein and their association on the protein (attack of the nucleophilic agent followed by the acception of the proton). This results in the formation of a cyclic peroxide in the amino acid residue and a C=O-->[C=O]* transition. The return of the carbonyl to the ground state makes it possible to store a part of free energy and use it for converting the enzyme to a state with a higher conformational energy. Thus, we consider the electron excited state in the protein as a state necessary for dark reactions. This implies that, in addition to the effect of sorption of substrate on protein, another aspect of behavior of the dynamic system should be taken into account. All factors producing a real effect on the internal protein dynamics are important for the conformational transition and enzymic reaction as a whole, and the rate constant should be determined with allowance for these factors.


Assuntos
Enzimas/metabolismo , Catálise , Cinética , Soluções
16.
Membr Cell Biol ; 14(5): 649-62, 2001 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-11699868

RESUMO

The work reviews membrane processes, such as monooxygenase reaction and oxidative phosphorylation with special reference to hydroxylation of a xenobiotic benzo(a)pyrene and the effects of the radical scavenger propyl gallate and radical generator Fe2+ ions on the reaction kinetics. A possibility is discussed that tocopherol provides for the activity of the lipid-radical cycles involving cytochrome b5. The lipid-radical cycles protect membrane lipids from oxidation and control the kinetics of membrane processes. The NADPH oxidation energy is transformed into the energy of lipid pulsations and this energy is used for activation of membrane enzymes. To account for the role of lipid pulsations in membrane processes, a new parameter is introduced - the internal temperature. It is supposed that there should be the equilibrium between the pro- and antioxidant factors in the membranes, and the presence of exogenous antioxidants (propyl gallate etc.) should be considered as a negative factor.


Assuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Citocromos b5/metabolismo , Membranas Intracelulares/enzimologia , Lipídeos de Membrana/metabolismo , Proteínas de Membrana/metabolismo , Microssomos/enzimologia , Mitocôndrias/enzimologia , Difosfato de Adenosina/metabolismo , Trifosfato de Adenosina/biossíntese , Animais , Antioxidantes/farmacologia , Benzo(a)pireno/metabolismo , Cátions/química , Cátions/farmacologia , Transporte de Elétrons , Ativação Enzimática , Ácidos Graxos Insaturados/metabolismo , Sequestradores de Radicais Livres/farmacologia , Radicais Livres , Hidroxilação , Ferro/química , Ferro/farmacologia , Peroxidação de Lipídeos , Potenciais da Membrana , Modelos Biológicos , NAD/metabolismo , NADP/metabolismo , NADPH Oxidases/metabolismo , Oxirredução , Fosforilação Oxidativa , Fosforilação , Galato de Propila/farmacologia , Conformação Proteica , Temperatura , Tocoferóis/farmacologia , Ubiquinona/metabolismo
17.
Biofizika ; 46(1): 60-8, 2001.
Artigo em Russo | MEDLINE | ID: mdl-11236564

RESUMO

The mechanism of coupling of the oxidation and activation of membrane enzymes was considered. It is obvious that microsomal monooxygenase uses the energy of NADPH oxidation for the activation of the terminal agent--cytochrome P-450. However, till now the mechanism of the transformation of this energy has not been discussed. It is supposed that the coupling process includes transformation of oxidation energy to kinetic energy, the energy of lipid pulsations. The mechanism proposed by us and the mechanism of energy transformation according to Mitchell are two independent mechanisms, both being of fundamental importance for biochemistry and biophysics of membranes. One approach uses the dielectric properties of membrane, and the other is based on the ability of hydrocarbon chains of phospholipids for rotamerization. A new empirical Arrhenius equation for membrane processes is offered. It accounts for the ability of membrane to reserve the energy in kinetic form (internal temperature). In conditions when membrane proteins cease to be acceptors of energy, the transfer of energy, i.e., transformation of the energy of NADPH oxidation into heat or light, occurs.


Assuntos
Membranas Intracelulares/metabolismo , Lipídeos de Membrana/metabolismo , Microssomos/metabolismo , Metabolismo Energético , Radicais Livres/metabolismo , Membranas Intracelulares/enzimologia , Ferro/metabolismo , Cinética , Bicamadas Lipídicas/metabolismo , Microssomos/enzimologia , Oxirredução , Termodinâmica , Vitamina E/metabolismo
18.
Biochimie ; 82(3): 237-44, 2000 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-10863007

RESUMO

Chemically initiated exchange (CIEE) luminescence reactions were reviewed and a new mechanism of luminescence with peracid as an intermediate is proposed; bacterial luminescence is generally considered to be a case of dioxetane luminescence, or, to be more precise, CIEE-luminescence which includes the generation of a cyclic peroxide. In the hypothesis the monooxygenase reaction (aldehyde -->fatty acid) should not be coupled with emitter generation as is usually believed, but only with the generation of peracid. As to the generation of the emitter, excited flavin, it is likely to occur later, during the interaction of flavin with cyclic peroxide. Its consequence is the breaking of two chemical bonds (O-O and C-C) in the cyclic peroxide and simultaneous generation of 4alpha-hydroxyflavin in exited state. In general, the generation of light includes three stages: 1) the monooxygenase reaction and the concurrent production of peracid; 2) the conversion of peracid to cyclic peroxide; and 3) the interaction of cyclic peroxide with flavin (through the CIEE mechanism).


Assuntos
Medições Luminescentes , Peróxidos/química , Espécies Reativas de Oxigênio
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