Reading model to estimate optimum economic intakes of amino acids for poultry

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Metabolomics method to comprehensively analyze amino acids in different domains

Amino acids play essential roles in both metabolism and the proteome. Many studies have profiled free amino acids (FAAs) or proteins; however, few have connected the measurement of FAA with individual amino acids in the proteome. In this study, we developed a metabolomics method to comprehensively analyze amino acids in different domains, using two examples of different sample types and disease models. We first examined the responses of FAAs and insoluble-proteome amino acids (IPAAs) to the Myc oncogene in Tet21N human neuroblastoma cells. The metabolic and proteomic amino acid profiles were quite different, even under the same Myc condition, and their combination provided a better understanding of the biological status. In addition, amino acids were measured in 3 domains (FAAs, free and soluble-proteome amino acids (FSPAAs), and IPAAs) to study changes in serum amino acid profiles related to colon cancer. A penalized logistic regression model based on the amino acids from the three domains had better sensitivity and specificity than that from each individual domain. To the best of our knowledge, this is the first study to perform a combined analysis of amino acids in different domains, and indicates the useful biological information available from a metabolomics analysis of the protein pellet. This study lays the foundation for further quantitative tracking of the distribution of amino acids in different domains, with opportunities for better diagnosis and mechanistic studies of various diseases.

Comparative study of the cathodic cleavage of N-tosyl- and N-nosyl-protected amino acids

The electrochemical behaviour of alanine and phenylalanine protected by the toluenesulphonyl (tosyl) and nitrobenzesulphonyl (nosyl) groups was examined in dimethyl formamide. The N-tosyl-protected amino acids are reduced in one cathodic step (-2.4 V/SCE) leading to cleavage of the SN bond after a two-electron transfer process. The N-nosyl-protected amino acids are reduced in three cathodic steps. Cyclic voltammetry and controlled potential electrolysis of N-nosyl amino acids have been used to probe the mechanism of these reductions in an aprotic medium and lead to cleavage of the SN bond in good yields ( > 60%) at -1.10 V/SCE. The comparative study of these compounds is used to comment on the applicability of the electrochemical method of removing protecting groups from amino acids. © 1993.

Oxidation of amino acids by chlorpromazine cation radical and co-catalysis by chlorpromazine

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Amino acids in squamous cell carcinomas and adjacent normal tissues from patients with larynx and oral cavity lesions

Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)

Effects of Diets Supplemented with Branched-Chain Amino Acids on the Performance and Fatigue Mechanisms of Rats Submitted to Prolonged Physical Exercise

This study aimed to determine the effects of diets chronically supplemented with branched-chain amino acids (BCAA) on the fatigue mechanisms of trained rats. Thirty-six adult Wistar rats were trained for six weeks. The training protocol consisted of bouts of swimming exercise (one hour a day, five times a week, for six weeks). The animals received a control diet (C) (n = 12), a diet supplemented with 3.57% BCAA (S1) (n = 12), or a diet supplemented with 4.76% BCAA (S2) (n = 12). On the last day of the training protocol, half the animals in each group were sacrificed after one hour of swimming (1H), and the other half after a swimming exhaustion test (EX). Swimming time until exhaustion was increased by 37% in group S1 and reduced by 43% in group S2 compared to group C. Results indicate that the S1 diet had a beneficial effect on performance by sparing glycogen in the soleus muscle (p < 0.05) and by inducing a lower concentration of plasma ammonia, whereas the S2 diet had a negative effect on performance due to hyperammonemia (p < 0.05). The hypothalamic concentration of serotonin was not significantly different between the 1H and EX conditions. In conclusion, chronic BCAA supplementation led to increased performance in rats subjected to a swimming test to exhaustion. However, this is a dose-dependent effect, since chronic ingestion of elevated quantities of BCAA led to a reduction in performance.

Nitrate reduces the negative effect of UV radiation on photosynthesis and pigmentation in Gracilaria tenuistipitata (Rhodophyta): the photoprotection role of mycosporine-like amino acids

Photoprotection of the agarophyte red alga Gracilaria tenuistipitata against ultraviolet radiation (UVR) was investigated in algae submitted for 1 week to photosynthetically active radiation (PAR, 260 mu mol photons m(-2) s(-1)) or PAR + UVR (UV-A, 8.13 W m(-2) and UV-B, 0.42 W m(-2)) under different nitrogen concentrations: 0, 0.1, and 0.5 mM of NO3-. Photosynthetic pigments decreased during the time of the experiment mainly under low nitrogen supply and UVR. Incubation under high nitrogen supply (0.5 mM) sustained the photosynthetic levels over time. In contrast, mycosporine-like amino acids (MAAs) increased up to eightfold in the presence of UVR and 0.5 mM NO3-. Under PAR + UVR, maximal quantum yield was positively correlated to MAA abundance, whereas under PAR no correlation was found. The photosynthetic yield of algae cultivated during seven days under PAR + UVR was less affected by a 30-min exposure of high UVR (16 W m(-2)) and fully recovered after transferring to low PAR irradiances, whereas algae kept under PAR were more affected by UV exposure and no full recovery was observed. Growth rates decreased after three days in the presence of UVR and under low nitrate supply. However, these rates were similar when compared with treatments of PAR and PAR + UVR after seven days, with the exception of samples in 0 mM NO3-, indicating that the acclimation after one week's exposure is related to nitrate supply. In conclusion, the lowest negative effect of UVR on photosynthesis and growth rate in high N-supply-grown algae could be explained by the stimulation of photoprotection mechanisms, such as accumulation of MAAs. Photostimulation of MAA accumulation by UVR under high N supply was observed in G. tenuistipitata even after 20 years in culture without the induction of this photomorphogenic light signal.

Avian coronavirus Spike Glycoprotein Ectodomain Shows a Low Codon Adaptation to Gallus gallus with Virus-Exclusive Codons in Strategic Amino Acids Positions

This is a study on the Avian coronavirus IBV and chicken host-relationship from the codon usage point of view based on fifty-nine non-redundant IBV S1 sequences (nt 1-507) from strains detected worldwide and chicken tissue-specific protein genes sequences from IBV-replicating sites. The effective number of codons (ENC) values ranged from 36 to 47.8, indicating a high-to-moderate codon usage bias. The highest IBV codon adaptation index (CAI) value was 0.7, indicating a distant virus versus host synonymous codons usage. The ENC x GC3 % curve indicates that both mutational pressure and natural selection are the driving forces on codon usage pattern in S1. The low CAI values agree with a low S protein expression and considering that S protein is a determinant for attachment and neutralization, this could be a further mechanism besides mRNA transcription attenuation for a low expression of this protein leading to an immune camouflage.

Thermodynamics of Axial Substitution and Kinetics of Reactions with Amino Acids for the Paddlewheel Complex Tetrakis(acetato)chloridodiruthenium(II,III)

The known paddlewheel, tetrakis(acetato)chloridodiruthenium(II,III), offers a versatile synthetic route to a novel class of antitumor diruthenium(II,III) metallo drugs, where the equatorial ligands are nonsteroidal anti-inflammatory carboxylates. This complex was studied here as a soluble starting prototype model for antitumor analogues to elucidate the reactivity of the [Ru-2(CH3COO)(4)](+) framework. Thermodynamic studies on equilibration reactions for axial substitution of water by chloride and kinetic studies on reactions of the diaqua complexes with the amino acids glycine, cysteine, histidine, and tryptophan were performed. The standard thermodynamic reaction parameters Delta H degrees, Delta S degrees, and Delta V degrees were determined and showed that both of the sequential axial substitution reactions are enthalpy driven. Kinetic rate laws and rate constants were determined for the axial substitution reactions of coordinated water by the amino acids that gave the corresponding aqua(amino acid)-Ru-2 substituted species. The results revealed that the [Ru-2(CH3COO)(4)](+) paddlewheel framework remained stable during the axial ligand substitution reactions and was also mostly preserved in the presence of the amino acids.

Endosymbiosis in trypanosomatids: the genomic cooperation between bacterium and host in the synthesis of essential amino acids is heavily influenced by multiple horizontal gene transfers

Background Trypanosomatids of the genera Angomonas and Strigomonas live in a mutualistic association characterized by extensive metabolic cooperation with obligate endosymbiotic Betaproteobacteria. However, the role played by the symbiont has been more guessed by indirect means than evidenced. Symbiont-harboring trypanosomatids, in contrast to their counterparts lacking symbionts, exhibit lower nutritional requirements and are autotrophic for essential amino acids. To evidence the symbiont’s contributions to this autotrophy, entire genomes of symbionts and trypanosomatids with and without symbionts were sequenced here. Results Analyses of the essential amino acid pathways revealed that most biosynthetic routes are in the symbiont genome. By contrast, the host trypanosomatid genome contains fewer genes, about half of which originated from different bacterial groups, perhaps only one of which (ornithine cyclodeaminase, EC:4.3.1.12) derived from the symbiont. Nutritional, enzymatic, and genomic data were jointly analyzed to construct an integrated view of essential amino acid metabolism in symbiont-harboring trypanosomatids. This comprehensive analysis showed perfect concordance among all these data, and revealed that the symbiont contains genes for enzymes that complete essential biosynthetic routes for the host amino acid production, thus explaining the low requirement for these elements in symbiont-harboring trypanosomatids. Phylogenetic analyses show that the cooperation between symbionts and their hosts is complemented by multiple horizontal gene transfers, from bacterial lineages to trypanosomatids, that occurred several times in the course of their evolution. Transfers occur preferentially in parts of the pathways that are missing from other eukaryotes. Conclusion We have herein uncovered the genetic and evolutionary bases of essential amino acid biosynthesis in several trypanosomatids with and without endosymbionts, explaining and complementing decades of experimental results. We uncovered the remarkable plasticity in essential amino acid biosynthesis pathway evolution in these protozoans, demonstrating heavy influence of horizontal gene transfer events, from Bacteria to trypanosomatid nuclei, in the evolution of these pathways.

Potential therapeutic effects of branched-chain amino acids supplementation on resistance exercise-based muscle damage in humans

Branched-chain amino acids (BCAA) supplementation has been considered an interesting nutritional strategy to improve skeletal muscle protein turnover in several conditions. In this context, there is evidence that resistance exercise (RE)-derived biochemical markers of muscle soreness (creatine kinase (CK), aldolase, myoglobin), soreness, and functional strength may be modulated by BCAA supplementation in order to favor of muscle adaptation. However, few studies have investigated such effects in well-controlled conditions in humans. Therefore, the aim of this short report is to describe the potential therapeutic effects of BCAA supplementation on RE-based muscle damage in humans. The main point is that BCAA supplementation may decrease some biochemical markers related with muscle soreness but this does not necessarily reflect on muscle functionality.

Synthesis of Modified Amino Acids and Insertion in Peptides and Mimetics. Structural Aspects and Impact on Biological Activity.

I studied the effects exerted by the modifications on structures and biological activities of the compounds so obtained. I prepared peptide analogues containing unusual amino acids such as halogenated, alkylated (S)- or (R)-tryptophans, useful for the synthesis of mimetics of the endogenous opioid peptide endomorphin-1, or 2-oxo-1,3-oxazolidine-4-carboxylic acids, utilized as pseudo-prolines having a clear all-trans configuration of the preceding peptide bond. The latter gave access to a series of constrained peptidomimetics with potential interest in medicinal chemistry and in the field of the foldamers. In particular, I have dedicated much efforts to the preparation of cyclopentapeptides containing D-configured, alfa-, or beta-aminoacids, and also of cyclotetrapeptides including the retro-inverso modification. The conformational analyses confirmed that these cyclic compounds can be utilized as rigid scaffolds mimicking gamma- or beta-turns, allowing to generate new molecular and 3D diversity. Much work has been dedicated to the structural analysis in solution and in the receptor-bound state, fundamental for giving a rationale to the experimentally determined bioactivity, as well as for predicting the activity of virtual compounds (in silico pre-screen). The conformational analyses in solution has been done mostly by NMR (2D gCosy, Roesy, VT, molecular dynamics, etc.). A special section is dedicated to the prediction of plausible poses of the ligands when bound to the receptors by Molecular Docking. This computational method proved to be a powerful tool for the investigation of ligand-receptor interactions, and for the design of selective agonists and antagonists. Another practical use of cyclic peptidomimetics was the synthesis and biological evaluation of cyclic analogues of endomorphin-1 lacking in a protonable amino group. The studies revealed that a inverse type II beta-turn on D-Trp-Phe constituted the bioactive conformation.

Novel porphyrin amino acids as building blocks for artificial photosynthetic reaction centers : photoinduced energy and electron transfer

This thesis reports on the synthesis and characterisation of trans-(M)AB2C meso-substituted porphyrin amino acid esters (PAr) (M = 2H or Zn) with tunable electron donating and electron withdrawing Ar substituents at B positions (Ar = 4-C6H4OnBu, 4-C6H4OMe, 2,4,6-C6H2Me3, 4-C6H4Me, C6H5, 4-C6H4F, 4-C6H4CF3, C6F5). These porphyrins were used as key building blocks for photosynthetic LHC (LHC = light-harvesting antenna complex) and RC (RC = reaction center) model compounds.rnBased on free-base or zinc(II) porphyrin amino acid esters and porphyrin acids several amide linked free-base bis(porphyrins) PAr1-PAr2 (Ar1 = 2,4,6-C6H2Me3, C6F5 and Ar2 = 2,4,6-C6H2Me3, 4-C6H4F, 4-C6H4CF3, C6F5), mono metallated bis(porphyrin) PAr1-(Zn)PAr2 (Ar1 = 2,4,6-C6H2Me3 and Ar2 =4-C6H4F) and its doubly zincated complexes (Zn)PAr1-(Zn)PAr2 were prepared. In the fluorescence spectra of free-base bis(porphyrins) the porphyrin with the strongest electron donating power of Ar substituents at B positions is the light emitting unity. The emission of mono metallated bis(porphyrin) occurs only from the free-base porphyrin building block. This phenomenon is caused by an efficient energy transfer likely via the Dexter through-bond mechanism.rnLinking of anthraquinone (Q) as electron acceptor (A) to the N-terminus of porphyrin amino acid esters ((M)PAr) and aminoferrocene (Fc) as electron donor (D) to the C-terminus of the porphyrin resulting in Q-(M)PAr-Fc triads (M = 2H or Zn, Ar = 4-C6H4OnBu, 4-C6H4OMe, 2,4,6-C6H2Me3, 4-C6H4Me, C6H5, 4-C6H4F, 4-C6H4CF3, C6F5) with tunable electron density at the porphyrin chromophore. In these triads initial oxidative PET (Q←(M)PAr) and reductive PET ((M)PAr→Fc) (PET = photoinduced electron transfer) are possible. Both processes leads to an emission quenching of (M)PAr. The efficiency of the PET pathways occurring in the Marcus normal region is controlled by the specific porphyrin electron density.rnAmide-linked conjugates PAr-Fc (Ar = 2,4,6-C6H2Me3, C6F5) and Fmoc-Fc-PAr1 (N-Fmoc-Fc = N-Fmoc protected 1,1’-ferrocene amino acid; Ar1 = C6H5, 4-C6H4F, 4-C6H4CF3, C6F5) as well as hinges PAr2-Fc-PAr1 (Ar1 = C6H5, 4-C6H4F and Ar2 = 2,4,6-C6H2Me3) were studied with respect to the reductive PET. The PET driving force (−GET) in dyads increases with the increasing electron withdrawing character of Ar substituents. Additionally, intramolecular energy transfer between porphyrins PAr1 and PAr2 is feasible in the hinges via the Förster mechanism.rn