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1.
Rev. bras. plantas med ; 16(3,supl.1): 765-770, 2014. tab
Article in Portuguese | LILACS | ID: lil-727207

ABSTRACT

O açafrão-da-terra (Curcuma longa L.) é originário do sudeste asiático e subcontinente indiano. É uma herbácea de caule subterrâneo, alaranjado, com vários rizomas secundários aproveitados na indústria alimentícia e farmacêutica devido às características de cor, sabor, odor, produção de óleos essenciais, e corantes. Na escolha do melhor material propagativo deve-se levar em consideração o material genético, o peso, tamanho, idade, capacidade de reserva acumulada, sanidade, dentre outros fatores. O objetivo neste experimento foi avaliar a influencia de diferentes acessos e pesos de rizomas-sementes na produção de açafrão. Empregou-se o delineamento em blocos casualizados em parcelas subdivididas com quatro repetições, tendo como tratamento principal os acessos (C-06, C-36 e C-38) e como tratamento secundário as classes de rizomas-sementes (peso): pequeno, médio e grande, ±5, ±10 e ±15 g/rizoma, respectivamente. Após a colheita, os rizomas foram distribuídos sobre tela suspensa para secagem à sombra com ventilação natural, por 20 dias. Posteriormente, para avaliar a produção, os rizomas foram classificados em 4 classes: A (> 15g ), B (±10 g), C (±5 g) e D(<5g). A interação entre os acessos e o tamanho do rizoma-semente foi significativa para todas as variáveis, com exceção da Classe D. Com o uso de rizoma-semente grande os acessos C-38 e o C-06 apresentaram maior produtividade total, 0,834 e 0,812kg/planta, respectivamente. O descarte gerado foi menor no acesso C-38 do que no C-06, representando 7,8 e 12,8% da produção total, respectivamente. O uso de rizomas-semente maiores aumentou significativamente a produção total. No acesso C-06 a produção passou de 0,481 para 0,812 kg/planta, ou seja, um aumento de 70%. O ganho relativo na produção de rizoma (kg/planta) no acesso C-06 para o plantio de rizomas com ±15 g, foi de 28%.


Turmeric (Curcuma longa L) originated in Southeast Asia and the Indian subcontinent. It is an herbaceous plant with underground, orange stem with several secondary rhizomes used in the food and pharmaceutical industries, because of its characteristics of color, taste, smell, production of essential oils and dyes. In cultivation, the best choice of propagation material must take account the genetic material, weight, age, accumulated reserve capacity, sanity, among other factors. In this study, seed-rhizomes of three weight categories - small, medium and large -, ± 05, ± 10 and ± 15 g / rhizome, respectively, of three genetic materials - C-06, C-36 and C-38 - from the Germplasm Bank of the ESALQ / USP were cultured from December 2009 to August 2010, at a spacing of 0.5 mx 0.2 m. After harvest, they were distributed on canvas suspended for drying in the shade and natural ventilation for 20 days. Later, to evaluate the production, they were classified into four categories: A (> 15g), B (± 10 g), C (± 5 g) and D (<5g) .The interaction between accessions and size of seed-rhizomes was significant for all variables, except for category D. With the use of large seed-rhizomes, C-38 and C-06 had a higher total yield, with 0.834 and 0.812 kg/plant, respectively. The use of large seed-rhizomes increased significantly the total production. In C-06, the production increased from 0.481 to 0.812 kg/plant, i.e. an increase of 70%. Also in C-06, the relative gain in the production of rhizome (kg / plant) for the planting of seed-rhizomes with ± 15 g was 28%.


Subject(s)
Weights and Measures/instrumentation , /pharmacology , Rhizome/classification , Seeds/anatomy & histology
2.
Arch Dis Child Fetal Neonatal Ed ; 95(4): F273-6, 2010 Jul.
Article in English | MEDLINE | ID: mdl-20388646

ABSTRACT

OBJECTIVE: To explore the influence of end-of-life decisions (EoL-D) on survival and mortality data in the light of differences reported among European countries. DESIGN: We collected the published data of several epidemiological studies: Epicure, Epipage, Epibel and the Norwegian study performed in the UK, France, Belgium and Norway, respectively. The data concerning the Epibel and Norwegian studies are considered for a preliminary analysis, while the data relating to the Epicure and Epipage studies are compared based on the total published data. The statistical analysis was performed through the class of generalised linear models, and more specifically, through log-linear models. The data considered were the number of babies who died in neonatal intensive care units after active withdrawal classified according to the country and gestational age. RESULTS The probability of death after active withdrawal was significantly higher at 22 and 24 weeks' gestational age compared with week 25, when considering both countries (OR, 2.35 and 1.29, respectively). For the week 23(0)-->(6), the probability of death after active withdrawal was not significant; however, it is relevant when considering the OR (1.31). When considering the country, there was a higher probability of death after active withdrawal in France than in the UK, or alternatively, with the assumed baseline French parameter, in the UK, there was a lower probability of death after active withdrawal, with a significant OR=0.69. CONCLUSIONS The attitude towards EoL-D could in part explain the differences in survival data of extremely preterm infants and should be taken in mind when comparing international survival rates.


Subject(s)
Infant Mortality , Infant, Premature , Refusal to Treat/statistics & numerical data , Attitude to Death , Cross-Cultural Comparison , Decision Making , Europe/epidemiology , Gestational Age , Humans , Infant, Newborn , Intensive Care Units, Neonatal/statistics & numerical data
3.
Biomed Pharmacother ; 59(6): 323-9, 2005 Jul.
Article in English | MEDLINE | ID: mdl-15935609

ABSTRACT

Nasal polyps are characterized by eosinophilic infiltration and presence of inflammatory mediators, such as total IgE, eosinophil cationic protein (ECP) and cytokines. The role of atopy in nasal polyp pathogenesis is still unclear. Therefore, we evaluated serum IgE levels, nasal mucus concentrations of ECP and cytokines and the number of infiltrating eosinophils in nasal tissue of polyps from atopic and non-atopic patients. Samples were obtained from a randomized population of 31 patients with nasal polyposis having endonasal sinus surgery and of 13 control subjects undergone corrective surgery of the nasal septum. On the basis of medical history of allergy, positive skin-prick tests and total IgE levels, patients with polyposis were divided in atopic (n = 13) and non-atopic (n = 18) patients. We determined levels of IgE in blood, ECP and cytokines (IL-4, IL-6, IL-8, IFN-gamma and IL-2) in nasal mucus, and number of infiltrating eosinophils in nasal tissue. The concentrations of total IgE, ECP, IL-4 and IL-8 and eosinophilia were significantly higher in all patients with nasal polyps compared with controls. Inside, all patients with nasal polyposis showed lower levels of IL-6, IFN-gamma and IL-2 compared with controls. The atopic patients showed significant differences when compared with non-atopic patients for the higher concentrations of total IgE (698.80+/-322.24 vs. 279.63+/-234.11; P < 0.0001) and IL-8 (1437.2 pg/ml+/-1250.7 vs. 605.5 pg/ml+/-481.1; P < 0.015). These findings suggest that inflammation still remains the major factor in the etiology of nasal polyposis and show different levels of inflammatory mediators into atopic and non-atopic patients.


Subject(s)
Eosinophilia/immunology , Hypersensitivity, Immediate/immunology , Inflammation Mediators/immunology , Nasal Polyps/immunology , Adult , Cytokines/immunology , Eosinophil Cationic Protein/blood , Eosinophil Cationic Protein/immunology , Eosinophilia/blood , Eosinophils/chemistry , Eosinophils/immunology , Eosinophils/pathology , Female , Flow Cytometry , Humans , Hypersensitivity, Immediate/blood , Immunoglobulin E/blood , Male , Middle Aged , Nasal Mucosa/chemistry , Nasal Mucosa/immunology , Nasal Mucosa/pathology , Nasal Polyps/blood
4.
Biochim Biophys Acta ; 1550(1): 64-9, 2001 Nov 26.
Article in English | MEDLINE | ID: mdl-11738088

ABSTRACT

The crystal structure of the specific carrier of retinol (retinol-binding protein, RBP) purified from chicken plasma has been determined (space group P2(1)2(1)2(1), with a=46.06(5) A, b=53.56(6) A, c=73.41(8) A, and one protein molecule in the asymmetric unit). Despite being obtained from a species phylogenetically distant from mammals, chicken holoRBP has an overall structure that closely resembles the previously determined structures of mammalian holoRBPs. The lack in chicken RBP of eight carboxy-terminal amino acid residues characteristic of mammalian RBPs does not significantly affect the protein structure. A distinctive feature of the avian protein is a better definition of the loop 63-67, close to the opening of the beta-barrel cavity accommodating the retinol molecule, which is rather disordered in the structures of mammalian RBPs.


Subject(s)
Chickens/blood , Retinol-Binding Proteins/chemistry , Animals , Models, Molecular , Prealbumin/chemistry , Protein Conformation , Retinol-Binding Proteins, Plasma , Thyroxine-Binding Proteins/chemistry , X-Ray Diffraction
6.
Physiol Behav ; 73(3): 351-8, 2001 Jun.
Article in English | MEDLINE | ID: mdl-11438361

ABSTRACT

In rat models of cardiac hypertrophy (moderate aortic coarctation: ACm, n=18; severe aortic coarctation: ACs, n=27; aging: OLD, n=25; spontaneous chronic hypertension: SHR, n=18) and properly matched control animals (C(ACm), n=17; C(ACs), n=19; C(OLD), n=24; C(SHR), n=22), we investigated the relative contribution of intense autonomic activity and cardiac structural damage to ventricular arrhythmogenesis. We used an "in vivo" to tissue level approach, by correlating in the same animal: (i) social stress-induced ventricular arrhythmias, telemetrically recorded, and (ii) left ventricular weights (LVW) and amount and geometrical properties of myocardial fibrosis (MF). Arterial blood pressure was significantly higher in ACm (+11%), ACs (+28%) and SHR (+34%) than in controls. LVW were approximately 20% greater in ACm, ACs and OLD and 50% greater in SHR. MF was about twice as great and characterized by more frequent occurrence of microscopic scarring in ACm and ACs, and eight times greater and associated with both a higher number and a larger size of fibrotic foci in OLD and SHR compared to controls. Social stress increased ventricular arrhythmia vulnerability in all models of cardiac hypertrophy, as well as in controls. The arrhythmogenic action of stress was facilitated in ACs, OLD and SHR. A correlation between structural cardiac remodeling and ventricular arrhythmias was found only in SHR and OLD, which exhibited the greatest increase in LVW and/or MF. Social stress proved to be a valuable tool for analyzing the combined effects of autonomic stimulation and altered myocardial substrate on the genesis of potentially life-threatening arrhythmias in social animals.


Subject(s)
Arrhythmias, Cardiac/pathology , Cardiomegaly/pathology , Stress, Psychological/psychology , Aging/psychology , Animals , Aortic Coarctation/pathology , Arrhythmias, Cardiac/etiology , Body Weight/physiology , Cardiomegaly/complications , Electrocardiography , Fibrosis/pathology , Interpersonal Relations , Myocardium , Organ Size/physiology , Rats , Rats, Wistar , Stress, Psychological/complications , Stress, Psychological/pathology , Telemetry
7.
Proc Natl Acad Sci U S A ; 98(7): 3710-5, 2001 Mar 27.
Article in English | MEDLINE | ID: mdl-11274389

ABSTRACT

Two cellular retinol-binding proteins (CRBP I and II) with distinct tissue distributions and retinoid-binding properties have been recognized thus far in mammals. Here, we report the identification of a human retinol-binding protein resembling type I (55.6% identity) and type II (49.6% identity) CRBPs, but with a unique H residue in the retinoid-binding site and a distinctively different tissue distribution. Additionally, this binding protein (CRBP III) exhibits a remarkable sequence identity (62.2%) with the recently identified iota-crystallin/CRBP of the diurnal gecko Lygodactylus picturatus [Werten, P. J. L., Röll, B., van Alten, D. M. F. & de Jong, W. W. (2000) Proc. Natl. Acad. Sci. USA 97, 3282-3287 (First Published March 21, 2000; 10.1073/pnas.050500597)]. CRBP III and all-trans-retinol form a complex (K(d) approximately 60 nM), the absorption spectrum of which is characterized by the peculiar fine structure typical of the spectra of holo-CRBP I and II. As revealed by a 2.3-A x-ray molecular model of apo-CRBP III, the amino acid residues that line the retinol-binding site in CRBP I and II are positioned nearly identically in the structure of CRBP III. At variance with the human CRBP I and II mRNAs, which are most abundant in ovary and intestine, respectively, the CRBP III mRNA is expressed at the highest levels in kidney and liver thus suggesting a prominent role for human CRBP III as an intracellular mediator of retinol metabolism in these tissues.


Subject(s)
Retinoids/metabolism , Retinol-Binding Proteins/isolation & purification , Amino Acid Sequence , Crystallography, X-Ray , Humans , Models, Molecular , Molecular Sequence Data , Protein Conformation , RNA, Messenger/metabolism , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Retinol-Binding Proteins/chemistry , Retinol-Binding Proteins/genetics , Retinol-Binding Proteins/metabolism , Retinol-Binding Proteins, Cellular , Sequence Homology, Amino Acid , Tissue Distribution
8.
Biochim Biophys Acta ; 1481(1): 103-8, 2000 Aug 31.
Article in English | MEDLINE | ID: mdl-11004580

ABSTRACT

Dihydrolipoate is an acceptor of the rhodanese-bound sulfane sulfur atom, as shown by analysis of the elementary steps of the reaction catalyzed by rhodanese. The crystal structure of sulfur-substituted rhodanese complexed with the non-reactive oxidized form of lipoate has revealed that the compound is bound at the enzyme active site, with the dithiolane ring buried in the interior of the cavity and the carboxylic end pointing towards the solvent. One of the sulfur atoms of the ligand in the unproductive complex is relatively close to the sulfane sulfur bound to Cys-247, the sulfur that is transferred during the catalytic reaction. This mode of binding of lipoate is likely to mimic that of dihydrolipoate. The results presented here support the possible role of dihydrolipoate as sulfur-acceptor substrate of rhodanese in an enzymatic reaction that might serve to provide iron-sulfur proteins with inorganic sulfide.


Subject(s)
Thioctic Acid/analogs & derivatives , Thiosulfate Sulfurtransferase/chemistry , Binding Sites , Crystallography , Fluorescence , Models, Chemical , Models, Molecular , Oxidation-Reduction , Substrate Specificity , Sulfur/chemistry , Thioctic Acid/chemistry
9.
Biochim Biophys Acta ; 1478(2): 232-8, 2000 May 23.
Article in English | MEDLINE | ID: mdl-10825534

ABSTRACT

Complement component C3 plays a key role in the complement-mediated immune defence, and occupies a central position within the complement cascade system. One of its degradation products, C3dg, was purified from rat serum and crystallised in two different crystal forms as N-terminally truncated fragment. Despite the truncation and the lack of a significant portion of the N-terminus as compared to C3d, the structure of the fragment is highly similar to that of recombinant human C3d (Nagar et al., Science 280 (1998) 1277-1281). Structural details of the reactive site have been obtained, suggesting a possible mode of thioester bond formation between Cys-1010 and Gln-1013 and thioester bond cleavage in the transacylation reaction involving His-1126. The truncation at the N-terminus of C3d leads to the exposure of a surface of the molecule that favours dimerisation, so that in both crystal forms, the fragment is present as a dimer, with monomers related by a two-fold axis.


Subject(s)
Complement C3d/chemistry , Animals , Complement C3d/immunology , Complement C3d/isolation & purification , Crystallization , Dimerization , Models, Molecular , Molecular Sequence Data , Peptide Fragments , Protein Conformation , Rats
10.
J Biol Chem ; 274(20): 13938-47, 1999 May 14.
Article in English | MEDLINE | ID: mdl-10318804

ABSTRACT

The NH2-terminal sequence of rhodanese influences many of its properties, ranging from mitochondrial import to folding. Rhodanese truncated by >9 residues is degraded in Escherichia coli. Mutant enzymes with lesser truncations are recoverable and active, but they show altered active site reactivities (Trevino, R. J., Tsalkova, T., Dramer, G., Hardesty, B., Chirgwin, J. M., and Horowitz, P. M. (1998) J. Biol. Chem. 273, 27841-27847), suggesting that the NH2-terminal sequence stabilizes the overall structure. We tested aspects of the conformations of these shortened species. Intrinsic and probe fluorescence showed that truncation decreased stability and increased hydrophobic exposure, while near UV CD suggested altered tertiary structure. Under native conditions, truncated rhodanese bound to GroEL and was released and reactivated by adding ATP and GroES, suggesting equilibrium between native and non-native conformers. Furthermore, GroEL assisted folding of denatured mutants to the same extent as wild type, although at a reduced rate. X-ray crystallography showed that Delta1-7 crystallized isomorphously with wild type in polyethyleneglycol, and the structure was highly conserved. Thus, the missing NH2-terminal residues that contribute to global stability of the native structure in solution do not significantly alter contacts at the atomic level of the crystallized protein. The two-domain structure of rhodanese was not significantly altered by drastically different crystallization conditions or crystal packing suggesting rigidity of the native rhodanese domains and the stabilization of the interdomain interactions by the crystal environment. The results support a model in which loss of interactions near the rhodanese NH2 terminus does not distort the folded native structure but does facilitate the transition in solution to a molten globule state, which among other things, can interact with molecular chaperones.


Subject(s)
Chaperonin 60/metabolism , Thiosulfate Sulfurtransferase/metabolism , Animals , Cattle , Crystallography, X-Ray , Enzyme Stability , Models, Molecular , Molecular Sequence Data , Molecular Structure , Protein Binding , Protein Conformation , Protein Folding , Structure-Activity Relationship
11.
Acta Crystallogr D Biol Crystallogr ; 55(Pt 1): 276-8, 1999 Jan.
Article in English | MEDLINE | ID: mdl-10089423

ABSTRACT

A macromolecular complex of human transthyretin, human retinol-binding protein and an anti-retinol-binding-protein Fab was crystallized by vapour diffusion in sitting drops. Diffraction from these crystals at cryogenic temperatures was consistent with the space group C222, with cell parameters a = 159.34, b = 222.40 and c = 121.27 A. Crystals diffracted to a resolution limit of 3.36 A using synchrotron radiation. Based on a 2:2:1 stoichiometry for the Fab-retinol-binding-protein-transthyretin complex and the presence of one such complex per asymmetric unit, a reasonable Vm coefficient of 2.74 A3 Da-1 could be estimated.


Subject(s)
Antigen-Antibody Complex/chemistry , Immunoglobulin Fab Fragments/chemistry , Prealbumin/chemistry , Prealbumin/immunology , Retinol-Binding Proteins/chemistry , Retinol-Binding Proteins/immunology , Animals , Antibodies, Monoclonal/chemistry , Antibodies, Monoclonal/isolation & purification , Antigen-Antibody Complex/isolation & purification , Crystallization , Humans , Immunoglobulin Fab Fragments/isolation & purification , Macromolecular Substances , Mice , Prealbumin/isolation & purification , Retinol-Binding Proteins/isolation & purification , X-Ray Diffraction
12.
Acta Crystallogr D Biol Crystallogr ; 54(Pt 5): 1049-52, 1998 Sep 01.
Article in English | MEDLINE | ID: mdl-9757135

ABSTRACT

The crystal structure of pig plasma retinol-binding protein (RBP) has been determined at 1.65 A resolution. The space group is P212121, with a = 45.81 (4), b = 53.14 (5), c = 72.97 (8) A and one protein molecule in the asymmetric unit. The structure has been solved using the molecular replacement method and refined with restrained least squares to an R factor of 0.1844 and an Rfree of 0.237 for 18 874 and 1001 independent reflections, respectively. The relatively high resolution structure of pig holoRBP has revealed some new structural details. Moreover, it has provided a description of the binding site for Cd2+, a metal ion which is required for protein crystallization. The hepta-coordination of the RBP-bound cadmium ion involves different residues of two symmetry-related RBP molecules, consistent with the participation of the cation in intermolecular interactions that in turn promote protein crystallization.


Subject(s)
Protein Conformation , Retinol-Binding Proteins/chemistry , Animals , Binding Sites , Cadmium/metabolism , Chromatography , Chromatography, Gel , Crystallization , Crystallography, X-Ray , Macromolecular Substances , Models, Molecular , Molecular Sequence Data , Retinol-Binding Proteins/isolation & purification , Retinol-Binding Proteins/metabolism , Retinol-Binding Proteins, Plasma , Swine , Vitamin A/metabolism
13.
Acta Crystallogr D Biol Crystallogr ; 54(Pt 4): 481-6, 1998 Jul 01.
Article in English | MEDLINE | ID: mdl-9761843

ABSTRACT

1.36 A resolution X-ray diffraction data have been recorded at 100 K for bovine liver sulfur-substituted rhodanese, using synchrotron radiation. The crystal structure has been refined anisotropically to a final R factor of 0.159 (Rfree = 0.229) for 53034 unique reflections. The model contains 2327 protein atoms and 407 solvent molecules, with a good geometry. The high resolution allows full details for helices, beta-sheets, tight turns and of all inter- and intramolecular interactions stabilizing the enzyme molecule to be given. The situation at the active site is described, particularly in regard to the network of hydrogen bonds made by Sgamma and Sdelta of the sulfur-substituted catalytic Cys247 and surrounding groups and solvent molecules. The replacement of the precipitant ammonium sulfate with cryoprotectants in the crystal-suspending medium led to the removal of the sulfate ion from the enzyme active site. Only limited changes of the enzyme structure have been found as a result of the drastic change in the crystal medium.


Subject(s)
Protein Conformation , Thiosulfate Sulfurtransferase/chemistry , Animals , Binding Sites , Cattle , Crystallography, X-Ray , Models, Molecular , Molecular Sequence Data , Solvents , Sulfur
15.
Biochem J ; 329 ( Pt 1): 101-6, 1998 Jan 01.
Article in English | MEDLINE | ID: mdl-9405281

ABSTRACT

The structure of a trigonal crystal form of N-terminally truncated [des-(1-9)] bovine annexin IV, an annexin variant that exhibits the distinctive property of binding both phospholipids and carbohydrates in a Ca2+-dependent manner, has been determined at 3 A (0.3 nm) resolution -space group: R3; cell parameters: a=b=118.560 (8) A and c=82.233 (6) A-. The overall structure of annexin IV, crystallized in the absence of Ca2+ ions, is highly homologous to that of the other known members of the annexin family. The trimeric assembly in the trigonal crystals of annexin IV is quite similar to that found previously in non-isomorphous crystals of human, chicken and rat annexin V and to the subunit arrangement in half of the hexamer of hydra annexin XII. Moreover, it resembles that found in two-dimensional crystals of human annexin V bound to phospholipid monolayers. The propensity of several annexins to generate similar trimeric arrays supports the hypothesis that trimeric complexes of such annexins, including annexin IV, may represent the functional units that interact with membranes.


Subject(s)
Annexin A4/chemistry , Amino Acid Sequence , Animals , Annexin A4/analogs & derivatives , Annexin A4/isolation & purification , Cattle , Crystallization , Crystallography, X-Ray , Hydrogen Bonding , Kidney/chemistry , Models, Molecular , Molecular Sequence Data , Phospholipids/metabolism , Protein Binding , Protein Conformation , Protein Structure, Secondary , Protein Structure, Tertiary
16.
J Biol Chem ; 271(35): 21054-61, 1996 Aug 30.
Article in English | MEDLINE | ID: mdl-8702871

ABSTRACT

In the course of the reaction catalyzed by rhodanese, the enzyme cycles between two catalytic intermediates, the sulfur-free and the sulfur-substituted (persulfide-containing) forms. The crystal structure of sulfur-free rhodanese, which was prepared in solution and then crystallized, is highly similar to that of sulfur-substituted enzyme. The inactivation of sulfur-free rhodanese with a small molar excess of hydrogen peroxide relies essentially on a modification limited to the active site, consisting of the oxidation of the essential sulfhydryl to sulfenyl group (-S-OH). Upon reaction of the sulfur-free enzyme with monoiodoacetate in the crystal, the Cys-247 side chain with the bound carboxymethyl group is forced into a conformation that allows favorable interactions of the carboxylate with the four peptide NH groups that participate in hydrogen bonding interactions with the transferable sulfur atom of the persulfide group in the sulfur-substituted rhodanese. It is concluded that active site-specific chemical modifications of sulfur-free rhodanese do not lead to significant changes of the protein structure, consistent with a high degree of similarity of the structures of the sulfur-free and sulfur-substituted forms of the enzyme both in solution and in the crystal.


Subject(s)
Thiosulfate Sulfurtransferase/metabolism , Animals , Binding Sites , Cattle , Crystallography, X-Ray , Liver/enzymology , Models, Molecular , Molecular Sequence Data , Oxidation-Reduction , Protein Conformation , Sulfur/chemistry , Thiosulfate Sulfurtransferase/chemistry
17.
Biochim Biophys Acta ; 1294(1): 48-54, 1996 May 02.
Article in English | MEDLINE | ID: mdl-8639713

ABSTRACT

The retinol carrier retinol-binding protein (RBP) forms a complex with the thyroid hormone binding protein transthyretin in the plasma of a number of vertebrate species. The interactions of retinoid-RBP complexes, as well as of unliganded RBP, with transthyretin have been investigated by means of fluorescence anisotropy studies. The presence of two independent and equivalent RBP binding sites per transthyretin molecule has been established for proteins purified from species distant in evolution. Although the natural ligand retinol participates in the interaction between retinol-RBP and transthyretin, its binding to RBP is not a prerequisite for protein-protein interaction. The dissociation constants of human transthyretin binding liganded and unliganded forms of human RBP were determined to be: all-trans retinol-RBP, Kd approximately 0.2 microM; apoRBP, Kd approximately 1.2 microM; all-trans retinoic acid-RBP, Kd approximately 0.8 microM; all-trans retinyl methyl ether-RBP, Kd approximately 6 microM. The complex of RBP with the synthetic retinoid fenretinide, which bears the bulky hydroxyphenyl end group, exhibits negligible affinity for transthyretin. The replacement of RBP-bound retinol with synthetic retinoids affects RBP-transthyretin recognition to an extent that appears to be well correlated with the nature and steric hindrance of the groups substituting the retinol hydroxyl group, consistent with their location at the interface between the contact areas of RBP and transthyretin.


Subject(s)
Prealbumin/metabolism , Retinoids/pharmacology , Retinol-Binding Proteins/metabolism , Animals , Antineoplastic Agents/metabolism , Antineoplastic Agents/pharmacology , Apoproteins/metabolism , Chickens , Dansyl Compounds/metabolism , Fenretinide/pharmacology , Fluorescence Polarization , Humans , Molecular Structure , Protein Binding/drug effects , Retinoids/metabolism , Retinol-Binding Proteins, Plasma , Thyroxine/metabolism , Tretinoin/metabolism , Vitamin A/analogs & derivatives , Vitamin A/metabolism , Vitamin A/pharmacology
18.
Eur J Biochem ; 234(2): 563-9, 1995 Dec 01.
Article in English | MEDLINE | ID: mdl-8536704

ABSTRACT

Retinoids are quite insoluble and chemically unstable compounds in the aqueous medium, such that natural retinoids need to be bound to specific retinoid-binding proteins to be protected, solubilized and transported in body fluids. All-trans retinoic acid exhibits a relatively high affinity for thyroxine-binding transthyretin in vitro and this protein is a good candidate for the transport of retinoic acid administered as pharmacological or antitumor agent. To define structural features essential for the recognition by transthyretin of a ligand which is structurally unrelated to thyroxine, we have cocrystallized human transthyretin with retinoic acid and determined its structure at 0.18-nm resolution. The retinoid fits into the two chemically identical thyroxine-binding sites, which are located in the central channel that runs through the tetrameric transthyretin. The cyclohexene ring of the bound retinoid is innermost, occupying the same position of the phenolic ring of the bound 3,3'-diiodo-L-thyronine, whereas the carboxylate group, like the same group of the thyroid hormone, participates in an ionic interaction with the Lys15 side chain at the entrance of the channel. Despite the fact that transthyretin was cocrystallized with all-trans-retinoic acid, the isoprene chain of the bound retinoid has been found in a non-extended conformation. This feature, that allows the carboxylate to orient in a manner suitable for ion-pair association with the Lys15 side chain, is attributable to the conversion of all-trans-retinoic acid into cis-isomers or folded conformers. It is concluded that the presence, in an essentially hydrophobic molecular core of the appropriate size, of a negatively charged group at the correct position is a crucial requirement for ligand-transthyretin recognition. Whereas the binding of the ligand has no remarkable consequences for the protein structure, all-trans-retinoic acid undergoes structural changes such as to interact favorably with residues present in the thyroxine-binding sites, resembling roughly the natural ligand.


Subject(s)
Prealbumin/chemistry , Tretinoin/chemistry , Binding Sites , Crystallization , Humans , Ligands , Prealbumin/metabolism , Protein Binding , Thyroxine/metabolism , Tretinoin/metabolism
19.
Minerva Med ; 86(5): 207-9, 1995 May.
Article in Italian | MEDLINE | ID: mdl-7566550

ABSTRACT

Measurement of serum bile acids was performed in 86 uremic patients without any liver or bile tract diseases. Thirty-six patients (23 males and 13 females, aged 21-60 years) were on conservative dietary treatment, whereas 50 uremics (31 males and 19 females, aged 23-82 years) were on maintenance hemodialysis. The assays were made by means of enzymatic procedure and confirmed by RIA method too. Elevated serum concentrations of bile acids (> 6 mumol/L) were found in 24 out of the 86 uremics (27.9%), and the prevalence was similar in patients on conservative (10/36, 27.7%) and on dialysis treatment (14/50, 28%). Then, abnormally elevated concentrations of circulating bile acids are present in a quite high percentage of uremics both on hemodialysis and on conservative dietary therapy. The existence of a subclinical liver disease or an abnormal entero-hepatic cycle of bile acids might explain these findings.


Subject(s)
Bile Acids and Salts/blood , Kidney Failure, Chronic/blood , Adult , Combined Modality Therapy , Female , Humans , Kidney Failure, Chronic/therapy , Male , Middle Aged , Renal Dialysis , Uremia/blood
20.
Eur J Biochem ; 229(2): 486-93, 1995 Apr 15.
Article in English | MEDLINE | ID: mdl-7744071

ABSTRACT

The interactions with retinol and retinol analogs of bovine cellular retinol-binding protein (CRBP) have been investigated, by means of fluorescence titrations, to obtain more information on the structural features of retinoid that may be required for their interaction with the binding protein. An approximately stoichiometric binding of retinol to bovine CRBP (K'd approximately 2 nM) has been found in direct binding assays. Although retinal exhibited relatively high binding affinity to bovine CRBP (K'd approximately 30 nM), a large excess of the retinoid could not compete with retinol for the carrier protein. On the assumption that retinol and retinal interact with the same binding site, this result indicates that the above-mentioned apparent dissociation constant for retinol.CRBP may be an overestimate and that its value may be as low as 0.1 nM. The finding of an exceedingly tight binding of retinol to CRBP provides further support for the possible role of CRBP-bound retinol, rather than its uncomplexed labile form, as substrate of enzymes involved in the metabolism of the vitamin. The results of these and previous studies indicate that CRBP is particularly sensitive to modifications of the retinol hydroxyl end group. Axerophthene, a retinol analog bearing a hydrogen atom in place of the hydroxyl end group, and beta-ionone exhibit rather low binding affinities for CRBP (K'd approximately 0.2 microM and approximately 4 microM, respectively), suggesting that the hydroxyl group and isoprene tail moieties contribute substantially to the retinol-binding affinity and specificity. These findings are consistent with the indications emerging from the three-dimensional structure determination of retinol.CRBP [Cowan, S. W., Newcomer, M. E. & Jones, T. A. (1993) J. Mol. Biol. 230, 1225-1246]. Additionally, the bulky end groups of fenretinide and N-ethyl retinamide replacing the retinol hydroxyl group have been found to prevent retinoid binding to CRBP. The primary structure of bovine CRBP has been determined and is highly similar to the structures of both human and rat CRBP (97% and 95% identical, respectively).


Subject(s)
Norisoprenoids , Retinoids/metabolism , Retinol-Binding Proteins/metabolism , Vitamin A/metabolism , Amino Acid Sequence , Animals , Binding, Competitive , Cattle , Diterpenes , Humans , Male , Molecular Sequence Data , Protein Binding , Rats , Retinaldehyde/metabolism , Retinol-Binding Proteins, Cellular , Sequence Alignment , Sequence Homology, Amino Acid , Terpenes/metabolism , Testis , Vitamin A/analogs & derivatives
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