[Metabolic correction: a biochemical option against diseases]. / Corrección metabólica: Una opción bioquímica contra las enfermedades.

Human development and its physiology depends on a number of complex biochemical body processes, many of which are interactive and codependent. The speed and the degree in which many physiological reactions are completed depend on enzyme activity, which in turn depends on the bioavailability of co-factors and micronutrients such as vitamins and minerals. To achieve a healthy physiological state, organism need that biochemical reactions occur in a controlled and specific way at a particular speed and level or grade fully completed. To achieve this, is required an optimal metabolic balance. Factors such as, a particular genetic composition, inadequate dietary consumption patterns, traumas, diseases, toxins and environmental stress all of these factors rising demands for nutrients in order to obtain optimal metabolic balance. Metabolic correction is a biochemical and physiological concept that explains how improvements in cellular biochemistry of an organism can help the body achieve metabolic and physiological optimization. We summarize the contribution of several pioneers in understanding the role of micronutrients in health management. The concept of metabolic correction is becoming a significant term due to the presence of genetic variants that affect the speed of reactions of enzymes, causing metabolic alterations that enhance or promote the state/development of multiple diseases. Decline in the nutritional value of the food we eat, the increase in demand for certain nutrients caused by normal development, diseases and medications induce, usually, nutrients consumption. These nutritional deficiencies and insufficiencies are causing massive economic costs due to increased morbidity and mortality in our society. In summary, metabolic correction improves the enzymatic function, which favors the physiological normal functions, thus, contributing to improving health and the welfare of the human being. The purpose of this paper is to describe and introduce the concept of optimal metabolic correction as a functional cost-effective mechanism against disease, in addition, to contribute to diseases prevention and regeneration of the body and health.

AepA of Pectobacterium is not involved in the regulation of extracellular plant cell wall degrading enzymes production.

Plant cell wall degrading enzymes (PCWDE) are the major virulence determinants in phytopathogenic Pectobacterium, and their production is controlled by many regulatory factors. In this study, we focus on the role of the AepA protein, which was previously described to be a global regulator of PCWDE production in Pectobacterium carotovorum (Murata et al. in Mol Plant Microbe Interact 4:239-246, 1991). Our results show that neither inactivation nor overexpression of aepA affects PCWDE production in either Pectobacterium atrosepticum SCRI1043 or Pectobacterium carotovorum subsp. carotovorum SCC3193. The previously published observation based on the overexpression of aepA could be explained by the presence of the adjacent regulatory rsmB gene in the constructs used. Our database searches indicated that AepA belongs to the YtcJ subfamily of amidohydrolases. YtcJ-like amidohydrolases are present in bacteria, archaea, plants and some fungi. Although AepA has 28% identity with the formamide deformylase NfdA in Arthrobacter pascens F164, AepA was unable to catalyze the degradation of NdfA-specific N-substituted formamides. We conclude that AepA is a putative aminohydrolase not involved in regulation of PCWDE production.

Efeito do processamento do alho (Allium sativum L. ) sobre os seus compostos bioativos e potencial antioxidante in vitro e in vivo / Effect of processing of garlic (Allium sativum L. ) on their bioactive compounds and antioxidant potential in vitro and in vivo

Introdução: O aumento do consumo de frutas e hortaliças está associado à redução do risco de ocorrência de doenças crônicas não transmissíveis. Este efeito protetor tem sido atribuído particularmente à presença de vários compostos bioativos como compostos fenólicos e organosulfurados, além de fitosteróis presentes no alho que podem contribuir com os efeitos antioxidante e hipolipemiante. Porém, o processamento do alho pode acarretar mudanças na quantidade e na efetividade dos compostos bioativos. Este trabalho teve como objetivo avaliar se a cocção e a fritura do alho reduziram as concentrações de compostos bioativos, o potencial antioxidante in vitro e in vivo em hamsters hipercolesterolemizados. Métodos: In vitro - foram determinados nos alhos cru, frito e cozido: a) composição centesimal (proteínas, lipídios, cinzas, carboidratos, fibra alimentar solúvel e insolúvel); b) perfil de ácidos graxos; c) teor de fenólicos totais; d) teor de quercetina, miricetina e apigenina; e) fitosteróis; f) alicina; g) teor de cobre, zinco e selênio; h) produtos intermediários da reação de Maillard; i) potencial antioxidante utilizando os testes ORAC (Oxygen radical absorbance capacity), Rancimat® e o sistema -caroteno/ácido linoléico. In vivo - hamsters machos foram distribuidos em 5 grupos com 10 animais em cada grupo. 1 - controle; 2 - hipercolesterolêmico; 3- hipercolesterolêmico e alho cru; grupo 4 - hipercolesterolêmico e alho cozido; grupo 5 - hipercolesterolêmico e alho frito. Os animais foram eutanasiados após 4 semanas de estudo para análises do plasma e do tecido hepático. No plasma foi determinado o potencial antioxidante pelo teste ORAC, o perfil lipídico (colesterol total e frações e triacilgliceróis) e verificado a atividade das enzimas aspartato aminotransferase (AST) e alanina aminotransferase (ALT). No tecido hepático foram avaliadas a atividade das enzimas hepáticas (glutationa peroxidase, catalase e superóxido dismutase) e o potencial antioxidante utilizando dois métodos, ORAC e ensaio cometa. Resultados: In vitro - O teor de fibras totais para o alho cru foi de 10,0por cento (71,6por cento é solúvel e 28,4por cento é insolúvel). O alto conteúdo de ácidos graxos trans no alho frito (14,9por cento ) é devido ao processo de fritura com 50por cento de gordura vegetal hidrogenada. A cocção não alterou o teor dos minerais analisados.

Dual function of rice OsDR8 gene in disease resistance and thiamine accumulation.

The function of OsDR8, a rice disease resistance-responsive gene, was studied. Silencing of OsDR8 using an RNA interference approach resulted in phenotypic alteration of the plants. The transgenic plants with repressed expression of OsDR8 showed reduced resistance or susceptibility to Xanthomonas oryzae pv. oryzae and Magnaporthe grisea causing bacterial blight and blast, which are two of the most devastating diseases in rice worldwide, respectively. The putative product of OsDR8 was highly homologous to an enzyme involved in the biosynthesis of the thiazole precursor of thiamine. Transgenic plants showing repressed expression of OsDR8 and reduced resistance had significantly lower levels of thiamine than the control plants. Exogenous application of thiamine could complement the compromised defense of the OsDR8-silenced plants. The expression level of several defense-responsive genes including the earlier functional genes of defense transduction pathway, OsPOX and OsPAL, and the downstream genes of the pathway, OsPR1a, OsPR1b, OsPR4, OsPR5 and OsPR10, was also decreased in the OsDR8-silenced plants. These results suggest that the impact of OsDR8 on disease resistance in rice may be through the regulation of expression of other defense-responsive genes and the site of OsDR8 function is on the upstream of the signal transduction pathway. In addition, the accumulation of thiamine may be essential for bacterial blight resistance and blast resistance.

Transcreener: screening enzymes involved in covalent regulation.

Enzymes that catalyse group transfer reactions comprise a significant fraction of the human proteome and are a rich source of drug targets because of their role in covalent regulatory cycles. Phosphorylation, glycosylation, sulfonation, methylation and acetylation represent some of the key types of group transfer reactions that modulate the function of diverse biomolecules through covalent modification. Development of high-throughput screening methods for these enzymes has been problematic because of the diversity of acceptor substrates. Recently, the authors developed a novel assay platform called Transcreener that relies upon fluorescence detection of the invariant reaction product of a group transfer reaction, usually a nucleotide. This platform enables screening of any isoform in a family of group transfer enzymes, with any acceptor substrate, using the same assay reagents.

In silico discovery of enzyme-substrate specificity-determining residue clusters.

The binding between an enzyme and its substrate is highly specific, despite the fact that many different enzymes show significant sequence and structure similarity. There must be, then, substrate specificity-determining residues that enable different enzymes to recognize their unique substrates. We reason that a coordinated, not independent, action of both conserved and non-conserved residues determine enzymatic activity and specificity. Here, we present a surface patch ranking (SPR) method for in silico discovery of substrate specificity-determining residue clusters by exploring both sequence conservation and correlated mutations. As case studies we apply SPR to several highly homologous enzymatic protein pairs, such as guanylyl versus adenylyl cyclases, lactate versus malate dehydrogenases, and trypsin versus chymotrypsin. Without using experimental data, we predict several single and multi-residue clusters that are consistent with previous mutagenesis experimental results. Most single-residue clusters are directly involved in enzyme-substrate interactions, whereas multi-residue clusters are vital for domain-domain and regulator-enzyme interactions, indicating their complementary role in specificity determination. These results demonstrate that SPR may help the selection of target residues for mutagenesis experiments and, thus, focus rational drug design, protein engineering, and functional annotation to the relevant regions of a protein.

Selenium and selenoproteins in mammals: extraordinary, essential, enigmatic.

Selenium (Se), once known only for its potential toxicity, is now well established as an essential trace element for mammals. Insufficient Se intake predisposes to and manifests in a variety of diseases. Recent studies have proven that it is the synthesis of selenocysteine (Sec)-containing proteins, designated selenoproteins, which represents an essential prerequisite for regular development and a long and healthy life. New transgenic mouse models analysing those selenoproteins with proven enzymatic functions displayed particular phenotypes and highlighted essential Se-dependent processes in development, growth or against specific challenges. While there is a growing molecular understanding of and general agreement on the importance of sufficiently high Se intake and undisturbed selenoprotein biosynthesis, many of the recently identified selenoproteins are still uncharacterised, and the effects and consequences of supra-physiological Se dosages are not biochemically understood. With the recent definition of the human and mouse selenoproteomes and a growing number of available tools, the Se field is now geared for a great leap forward. Se biology has already broadened our knowledge about the genetic code and about protein translation. It now holds great promises also for a better understanding of some key aspects of cancer, inflammation, fertility and prevention of age-associated diseases.

High-dose vitamin therapy stimulates variant enzymes with decreased coenzyme binding affinity (increased K(m)): relevance to genetic disease and polymorphisms.

As many as one-third of mutations in a gene result in the corresponding enzyme having an increased Michaelis constant, or K(m), (decreased binding affinity) for a coenzyme, resulting in a lower rate of reaction. About 50 human genetic dis-eases due to defective enzymes can be remedied or ameliorated by the administration of high doses of the vitamin component of the corresponding coenzyme, which at least partially restores enzymatic activity. Several single-nucleotide polymorphisms, in which the variant amino acid reduces coenzyme binding and thus enzymatic activity, are likely to be remediable by raising cellular concentrations of the cofactor through high-dose vitamin therapy. Some examples include the alanine-to-valine substitution at codon 222 (Ala222-->Val) [DNA: C-to-T substitution at nucleo-tide 677 (677C-->T)] in methylenetetrahydrofolate reductase (NADPH) and the cofactor FAD (in relation to cardiovascular disease, migraines, and rages), the Pro187-->Ser (DNA: 609C-->T) mutation in NAD(P):quinone oxidoreductase 1 [NAD(P)H dehy-drogenase (quinone)] and FAD (in relation to cancer), the Ala44-->Gly (DNA: 131C-->G) mutation in glucose-6-phosphate 1-dehydrogenase and NADP (in relation to favism and hemolytic anemia), and the Glu487-->Lys mutation (present in one-half of Asians) in aldehyde dehydrogenase (NAD + ) and NAD (in relation to alcohol intolerance, Alzheimer disease, and cancer).

Contrasting effects of fish oil and safflower oil on hepatic peroxisomal and tissue lipid content.

To examine the mechanism by which fish oil protects against fat-induced insulin resistance, we studied the effects of control, fish oil, and safflower oil diets on peroxisomal content, fatty acyl-CoA, diacylglycerol, and ceramide content in rat liver and muscle. We found that, in contrast to control and safflower oil-fed rats, fish oil feeding induced a 150% increase in the abundance of peroxisomal acyl-CoA oxidase and 3-ketoacyl-CoA thiolase in liver but lacked similar effects in muscle. This was paralleled by an almost twofold increase in hepatic peroxisome content (both P < 0.002 vs. control and safflower). These changes in the fish oil-fed rats were associated with a more than twofold lower hepatic triglyceride/diacylglycerol, as well as intramuscular triglyceride/fatty acyl-CoA, content. In conclusion, these data strongly support the hypothesis that n-3 fatty acids protect against fat-induced insulin resistance by serving as peroxisome proliferator-activated receptor-alpha ligands and thereby induce hepatic, but not intramuscular, peroxisome proliferation. In turn, an increased hepatic beta-oxidative capacity results in lower hepatic triglyceride/diacylglycerol and intramyocellular triglyceride/fatty acyl-CoA content.

Antioxidants and exercise.

Muscular exercise results in an increased production of radicals and other forms of reactive oxygen species. Further more, growing evidence implicates cytotoxic ROS as an underlying cause in exercise-induced disturbances in muscle redox status that could result in muscle fatigue or injury. Muscle cells contain complex cellular defense mechanisms to minimize the risk for oxidative injury. Two major classes of endogenous protective mechanisms work together to reduce the harmful effects of oxidants in the cell: (1) enzymatic and (2) nonenzymatic antioxidants. Key antioxidant enzymes include superoxide dismutase, glutathione peroxidase, and catalase. These enzymes are responsible for removing superoxide radicals, hydrogen peroxide or organic hydroperoxides, and hydrogen peroxide, respectively. Important nonenzymatic antioxidants include vitamins E and C, beta-carotene, GSH, uric acid, ubiquinone, and bilirubin. Vitamin E, beta-carotene, and ubiquinone are located in lipid regions of the cell, whereas uric acid, GSH, and bilirubin are in aqueous compartments of the cell. Although numerous animal experiments have demonstrated that the addition of antioxidants can improve muscular performance, to date, limited evidence shows that dietary supplementation with antioxidants improves human performance. This is an important area for future research.

Role and significance of enzymes in human milk.

Although human milk generally contains higher levels of enzymes than bovine milk, little definitive information is available concerning their role or significance. The enzyme levels in human milk as compared to bovine milk and levels in human colostrum versus normal milk are summarized. The few most widely studied human milk enzymes are discussed in more detail. Evidence is presented to support the views that 1) lipoprotein lipase and ribonuclease are probably spilled into the milk from the blood; 2) lysozyme is spilled from the secretory epithelial cells; 3) lactate and malate dehydrogenases, glucose-6-phosphate dehydrogenase, and lactose synthetase are synthesized in the mammary gland in response to hormonal stimuli; and 4) bile salt stimulated lipase, diastase, protease, and lysozyme are present in sufficient quantities to aid infants in growth and nutrition. Consideration must be given to standardizing the various enzyme assay procedures and activity units so that meaningful comparisons between various studies could be made.

Drug latentiation in cancer chemotherapy.

Latent antitumour agents require spontaneous or enzyme-catalysed activation to cytotoxic species in vivo. Activation may occur principally in normal tissues or in the target tumour. Agents of this type are discussed and mechanisms of drug action and selectivity are described, with reference to appropriate examples. The comparatively poor therapeutic activity of many agents designed for selective activation in tumours is attributed to the often unfavourable distribution of activating enzymes between normal and neoplastic tissues. Factors to be considered in the design of new enzyme-activated agents are discussed and possible artefacts involved in the assay of tumour enzymes are described. Some novel approaches to the design of latent antitumour agents are also discussed.