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1.
Clin Exp Allergy ; 48(1): 13-22, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29130617

RESUMO

BACKGROUND: Subsets of patients with severe asthma remain symptomatic despite prolonged, high-dose glucocorticoid therapy. We hypothesized that the clinical glucocorticoid sensitivity of these asthmatics is reflected in differences in peripheral blood dendritic cell subsets. OBJECTIVE: To compare peripheral blood leucocyte populations using flow cytometry at baseline and after 2 weeks of systemic glucocorticoid (steroid) treatment to identify immunological differences between steroid-sensitive (SS) and steroid-resistant (SR) asthmatics. METHODS: Adult severe asthmatics (SS n = 12; SR n = 23) were assessed for their response to 2 weeks of therapy with oral prednisolone. Peripheral blood was obtained before and after therapy and stained for lymphocyte (CD3, CD19, CD4, CD8 and Foxp3) and dendritic cell markers (Lineage negative [CD3, CD14, CD16, CD19, CD20, CD56], HLA-DR+, CD304, CD11c, ILT3 and CD86). RESULTS: A higher median frequency of myeloid DCs (mDCs) but not plasmacytoid DCs (pDCs) was observed in the blood of SR as compared to SS asthmatics (P = .03). Glucocorticoid therapy significantly increased median B cell, but not T cell numbers in both cohorts, with a trend for increased numbers of Foxp3+ Tregs in SS (P = .07), but not SR subjects. Oral prednisolone therapy significantly reduced the median numbers and frequencies of total DCs and pDCs in both SS and SR asthmatics. Interestingly, the expression of HLA-DR and ILT3 was also reduced on pDCs in all patients. In contrast, therapy increased the median frequency of mDCs in SS, but reduced it in SR asthmatics. CONCLUSIONS: Myeloid DC frequency is elevated in SR compared with SS asthmatics, and mDC shows a differential response to oral prednisolone therapy.


Assuntos
Antígenos CD/imunologia , Células Dendríticas/imunologia , Glucocorticoides/administração & dosagem , Prednisolona/administração & dosagem , Linfócitos T/imunologia , Administração Oral , Adulto , Asma/tratamento farmacológico , Asma/imunologia , Asma/patologia , Células Dendríticas/patologia , Feminino , Citometria de Fluxo , Humanos , Masculino , Linfócitos T/patologia
3.
Bioresour Technol ; 97(6): 809-18, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15990288

RESUMO

On-farm production of arbuscular mycorrhizal (AM) fungus inoculum can reduce the cost of the inoculum and increase utilization of this symbiosis in plant production. Bahiagrass (Paspalum notatum Flugge) seedlings, colonized by AM fungi, were transplanted into raised bed enclosures. Media within the enclosures was vermiculite mixed with either field soil or yard clippings compost in Experiment I and vermiculite mixed with yard clippings compost or dairy manure/leaf compost in Experiment II. Compost and vermiculite mixtures yielded more propagules of AM fungi than soil-based mixtures in Experiment I. Growth of plants in a 1:4 (v/v) mixture of yard clippings compost and vermiculite produced more inoculum (503 propagules cm(-3)) than growth in 1:9 and 1:99 (v/v) mixtures (240 and 42 propagules cm(-3), respectively). Water, inorganic nutrient solution minus P, and fish protein digest were added to inoculum production enclosures in Experiment II. Results indicated that supplemental nutrient addition was unnecessary. This method produces a concentrated inoculum of AM fungi in a form readily used as an amendment to horticultural potting media for the production of vegetable seedlings.


Assuntos
Agricultura/métodos , Micorrizas/fisiologia , Microbiologia do Solo , Microbiologia Industrial/métodos , Paspalum/microbiologia , Solo
4.
Biochim Biophys Acta ; 1054(2): 169-75, 1990 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-2400781

RESUMO

Three 133Cs-NMR signals were observed in the spectra of CsCl-perfused and CsCl-grown maize seedling root tips. Two relatively broad lower field resonances were assigned to the subcellular, compartmented Cs+ in the cytoplasm and vacuole, respectively. The rate of area increase of the broader cytoplasmic Cs resonance was about 9-times faster than that of the vacuolar signal during the first 300 min of tissue perfusion with CsCl. In addition, the spin lattice relaxation time of the cytoplasmic Cs resonance was approx. 3-times shorter than that of the extracellular resonance, while the Cs+ signal associated with the metabolically less active vacuolar compartment exhibited a relaxation time comparable to that of the extracellular signal. 133Cs spectra of excised, maize root tips and excised top sections of the root adjacent to the kernel, each grown in 10 mM CsCl showed a difference in the relative areas of the Cs resonance corresponding to the distinct cytoplasm/vacuole volume ratio of these well differentiated sections of the root. The high correlation of counterion concentration with 133Cs chemical shifts suggested that the larger downfield shift exhibited by the cytoplasmic confined Cs+ was due principally to the higher ionic strength and protein content in this compartment. Such observations indicate that 133Cs-NMR might be employed for studying ionic strength, and osmotic pressure associated chemical shifts and the transport properties of Cs+ (perhaps as an analogue for K+) in subcellular compartments of plant tissues.


Assuntos
Compartimento Celular , Zea mays/metabolismo , Transporte Biológico , Isótopos de Césio , Citoplasma/metabolismo , Espectroscopia de Ressonância Magnética , Vacúolos/metabolismo , Zea mays/crescimento & desenvolvimento
5.
Biochim Biophys Acta ; 1116(3): 215-25, 1992 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-1610877

RESUMO

In our previous in vivo 31P study of intact nitrogen-fixing nodules (Rolin, D.B., Boswell, R.T., Sloger, C., Tu, S.I. and Pfeffer, P.E., 1989 Plant Physiol. 89, 1238-1246), we observed an unknown phosphodiester. The compound was also observed in the spectra of isolated bacteroids as well as extracts of the colonizing Bradyrhizobium japonicum USDA 110. In order to characterize the phosphodiester in the present study, we took advantage of the relatively hydrophobic nature of the material and purified it by elution from a C-18 silica reverse-phase chromatography column followed by final separation on an aminopropyl silica HPLC column. Structural characterization of this compound with a molecular weight of 2271 (FAB mass spectrometry), using 13C-1H and 31P-1H heteronuclear 2D COSY and double quantum 2D phase sensitive homonuclear 1H COSY NMR spectra, demonstrated that the molecule contained beta-(1,3); beta-(1,6); beta-(1,3,6) and beta-linked non-reducing terminal glucose units in the ratio of 5:6:1:1, respectively, as well as one C-6 substituted phosphocholine (PC) moiety associated with one group of (1,3) beta-glucose residues. Carbohydrate degradation analysis indicated that this material was a macrocyclic glucan, (absence of a reducing end group) with two separated units containing three consecutively linked beta-(1,3) glucose residues and 6 beta-(1,6) glucose residues. The sequences of beta-(1,3)-linked glucose units contained a single non-reducing, terminal, unsubstituted glucose linked at the C-6 position and a PC group attached primarily to an unsubstituted C-6 position of a beta-(1,3)-linked glucose.


Assuntos
Glucanos/química , Fosforilcolina/química , Rhizobiaceae/química , Sequência de Carboidratos , Cromatografia Líquida de Alta Pressão , Glucanos/isolamento & purificação , Glucanos/metabolismo , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Dados de Sequência Molecular , Estrutura Molecular , Fixação de Nitrogênio , Rhizobiaceae/metabolismo
6.
Plant Physiol ; 108(1): 7-15, 1995 May.
Artigo em Inglês | MEDLINE | ID: mdl-12228450

RESUMO

Vesicular-arbuscular mycorrhizal fungi are symbionts for a large variety of crop plants; however, the form in which they take up carbon from the host is not established. To trace the course of carbon metabolism, we have used nuclear magnetic resonance spectroscopy with [13C]glucose labeling in vivo and in extracts to examine leek (Allium porrum) roots colonized by Glomus etunicatum (and uncolonized controls) as well as germinating spores. These studies implicate glucose as a likely substrate for vesicular-arbuscular mycorrhizal fungi in the symbiotic state. Root feeding of 0.6 mM 1-[13C]glucose labeled only the fungal metabolites trehalose and glycogen. The time course of this labeling was dependent on the status of the host. Incubation with 50 mM 1-[13C]glucose caused labeling of sucrose (in addition to fungal metabolites) with twice as much labeling in uncolonized plants. There was no detectable scrambling of the label from C1 glucose to the C6 position of glucose moieties in trehalose or glycogen. Labeling of mannitol C1,6 in the colonized root tissue was much less than in axenically germinating spores. Thus, carbohydrate metabolism of host and fungus are significantly altered in the symbiotic state.

7.
J Cyst Fibros ; 2(2): 61-8, 2003 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15463851

RESUMO

Increasing numbers of cystic fibrosis (CF) patients are surviving into adulthood. An understanding of the psychiatric and psychosocial aspects of CF in adults and adolescents is therefore more important than ever. There is a large body of evidence indicating that the psychological and psychosocial functioning of people with CF is similar to that of well people, until the disease becomes severe. However, there is also evidence that patients do suffer an increased likelihood of psychiatric problems, such as depression, and of scoring poorly on physical functioning measures of quality of life. Studies have found conflicting evidence as to any association between degree of respiratory impairment and psychological functioning. Coping styles seem to have a large effect upon the quality of life of CF patients. People with cystic fibrosis can have problems with sexuality, platonic relationships and independence. Families of patients also suffer problems, which can affect the patients themselves. Non-compliance is a complicated problem with many patients. New treatments for people with CF are emerging, such as lobe transplants from live donors and gene therapy, with possible new psychosocial problems resulting. Furthermore, older studies are becoming increasingly inapplicable as treatment and prognosis changes. Therefore, more research is needed in this field.


Assuntos
Fibrose Cística/psicologia , Transtornos Mentais , Saúde Mental , Atividades Cotidianas , Adaptação Psicológica , Adolescente , Adulto , Fatores Etários , Atitude Frente a Saúde , Fibrose Cística/complicações , Fibrose Cística/terapia , Família/psicologia , Fertilidade , Nível de Saúde , Humanos , Relações Interpessoais , Transtornos Mentais/etiologia , Transtornos Mentais/psicologia , Psicologia do Adolescente , Qualidade de Vida , Fatores de Risco , Fatores Sexuais , Comportamento Sexual , Comportamento Social , Apoio Social , Sobreviventes/psicologia
8.
Carbohydr Res ; 226(1): 29-42, 1992 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-1499020

RESUMO

The 13C CPMAS n.m.r. spectrum of 4-O-beta-D-galactopyranosyl-D-fructose (lactulose) trihydrate, C12H22O11.3 H2O, identifies the isomer in the crystals as the beta-furanose. This is confirmed by a crystal structure analysis, using CuK alpha X-ray data at room temperature. The space group is P212121, with Z = 4 and cell dimensions a = 9.6251(3), b = 12.8096(3), c = 17.7563(4) A. The structure was refined to R = 0.031 and Rw 0.025 for 1929 observed structure amplitudes. All the hydrogen atoms were unambigously located on difference syntheses. The conformation of the pyranose ring is the normal 4C1 chair and that of the furanose ring is 4T3. The 1----4 linkage torsion angles are O-5'-C-1'-O-1'-C-4 = 79.9(2) degrees and C-1'-O-1'-C-4-C-5 = -170.3(2) degrees. All hydroxyls, ring and glycosidic oxygens, and water molecules are involved in the hydrogen bonding, which consists of infinite chains linked together by water molecules to form a three-dimensional network. There is a three-centered intramolecular, interresidue hydrogen bond from O-3-H to O-5' and O-6'. The n.m.r. spectrum of the amorphous, dehydrated trihydrate suggests the occurrence of a solid-state reaction forming the same isomeric mixture as was observed in crystalline anhydrous lactulose, although the mutarotation of the trihydrate when dissolved in Me2SO is very slow.


Assuntos
Lactulose/química , Configuração de Carboidratos , Sequência de Carboidratos , Cristalografia , Ligação de Hidrogênio , Isomerismo , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Dados de Sequência Molecular , Água/química
9.
Carbohydr Res ; 296: 23-37, 1996 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-9008841

RESUMO

A unique glucan has been isolated from a recombinant strain of a Rhizobium meliloti TY7, a cyclic beta-(1-->2) glucan mutant carrying a locus specifying beta-(1-->3; 1-->6) glucan synthesis from Bradyrhizobium japonicum USDA110. This compound, which appears to have considerable hydrophobic affinity, was separated from a perchloric acid cell extract by adsorption to a C-18 silica column. Unlike those cyclic glucans previously isolated from Rhizobium meliloti or Bradyrhizobium japonicum, this molecule contains neither phosphoglycerol nor phosphocholine substituents, respectively. 2D NMR, FAB mass spectrometric analysis and high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) confirmed that this glucan is a single, cyclic decasaccharide (cyclolaminarinose) in which one of the residues is substituted in its 6-position with beta-laminarabiose. This structural assignment was confirmed by mass spectral and NMR analyses of the product obtained from two consecutive Smith degradations. Unlike the complex 13C spectrum of the unoxidized material, the spectrum of this product consisted of only six resonances due to rapid time averaging of its symmetrical structure on the relatively slow NMR timescale. Synthesis of this newly described cyclic beta-glucan in the R. meliloti ndvB mutant restored the symbiotic and hypoosmotic adaptation characteristics of the R. meliloti wild type strain.


Assuntos
Glucanos/química , Sinorhizobium meliloti/química , Configuração de Carboidratos , Sequência de Carboidratos , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Dados de Sequência Molecular , Estrutura Molecular , Oligossacarídeos/química
10.
Carbohydr Res ; 256(1): 13-27, 1994 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-8194069

RESUMO

The inclusion complexes of cyclomaltohexaose (alpha-CD), cyclomaltoheptaose (beta-CD), cyclomaltooctaose (gamma-CD), and polymerized beta-CD (beta-CDn) with chlorogenic acid (CA), the major substrate of apple fruit polyphenol oxidase (PPO), were studied with regard to pH, ionic strength, and temperature in model buffer systems and apple juice. The thermodynamics of CD.CA inclusion complex formation, which were studied in solution using UV spectrophotometry, displayed enthalpy-entropy compensation typical of processes driven by solvation phenomena. We also found that the apparent association constants (K) of the CD.CA equilibrium were relatively insensitive to pH for beta-CD, compared to alpha- and gamma-CDs, but were subject to substantial enhancement at low ionic strengths. The beta-CD.CA inclusion complex was also characterized for binding geometry and stoichiometry at 9.4 T and 25 degrees C in 0.05 M Na phosphate buffer by 1H NMR spectroscopy. A 1:1 stoichiometric ratio for the complex was found using the method of continuous variations. 1H Spin-lattice relaxation and chemical-shift data indicate that the phenolic ring of CA docks within the cavity of beta-CD. The Ks for beta-, alpha-, and gamma-CD determined in apple juice, which contains a mixture of PPO substrates, were found to correlate with PPO activity-related data. Apple juice, treated with beta-CDn, did not brown until CA was added back. These latter findings strongly argue that the mechanism for inhibition of juice browning with cyclodextrins was mainly due to the binding of PPO substrates and not some other means such as enzyme inactivation via sequestration of Cu2+ by CDs.


Assuntos
Catecol Oxidase/química , Ciclodextrinas/química , Frutas/enzimologia , Sítios de Ligação , Configuração de Carboidratos , Sequência de Carboidratos , Catecol Oxidase/metabolismo , Ciclodextrinas/metabolismo , Cinética , Espectroscopia de Ressonância Magnética , Matemática , Dados de Sequência Molecular , Espectrofotometria Ultravioleta , Especificidade por Substrato , Termodinâmica
11.
Lipids ; 12(10): 869-71, 1977 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27519629

RESUMO

The amount of butyrate contained in a complex mixture of butter oil triglycerides was 10.3 mole % as determined by natural abundance(13)C Fourier transform pulse nuclear magnetic resonance (NMR) spectroscopy. This NMR technique also demonstrated the primary isomeric positioning (>97%) of the butyrl group without the need for altering or fractionating the fat mixture.

12.
Lipids ; 27(4): 285-8, 1992 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-1518386

RESUMO

Substitution of a hydroxyl group at the bis homoallylic position (OH group located three carbons away from the olefinic carbon) in C18 unsaturated fatty acid esters (FAE) induces a 0.73 +/- 0.05 ppm upfield and a 0.73 +/- 0.06 ppm downfield shift on the delta and epsilon olefinic 13C resonances relative to the unsubstituted FAE, respectively. If the hydroxyl group is located on the carboxyl side of the double bond of the bis homoallylic hydroxy fatty acid esters (BHAHFA), the olefinic resonances are uniformly shifted apart by [formula: see text] where delta delta dbu represents the absolute value of the double bond resonance separation in the unsubstituted FAE and 1.46 ppm is the sum of the absolute values of the delta and epsilon shift parameters. With hydroxyl substitution on the terminal methyl side of the double bond, the olefinic shift separation is equal to [formula: see text] In homoallylic (OH group located two carbons away from the olefinic carbon) substituted FAE the gamma and delta induced hydroxyl shifts for the cis double bond resonances are +3.08 and -4.63 ppm, respectively while the trans double bond parameters are +4.06 and -4.18 ppm, respectively. The double bond resonance separation in homoallylic hydroxy fatty acid esters (HAHFA) can be calculated from the formula [formula: see text] for cis and [formula: see text] for the trans case when the OH substitution is on the carboxyl side of the double bond. Conversely, when the OH resides on the terminal methyl side, the double bond shift separations for cis and trans isomers are [formula: see text] and [formula: see text] respectively.(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Ácidos Graxos Insaturados/química , Algoritmos , Isótopos de Carbono , Ésteres , Espectroscopia de Ressonância Magnética
14.
New Phytol ; 168(3): 687-96, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16313650

RESUMO

Nitrogen (N) is known to be transferred from fungus to plant in the arbuscular mycorrhizal (AM) symbiosis, yet its metabolism, storage and transport are poorly understood. In vitro mycorrhizas of Glomus intra-radices and Ri T-DNA-transformed carrot roots were grown in two-compartment Petri dishes. (15)N- and/or (13)C-labeled substrates were supplied to either the fungal compartment or to separate dishes containing uncolonized roots. The levels and labeling of free amino acids (AAs) in the extra-radical mycelium (ERM) in mycorrhizal roots and in uncolonized roots were measured by gas chromatography/mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC). Arginine (Arg) was the predominant free AA in the ERM, and almost all Arg molecules became labeled within 3 wk of supplying (15)NH(4) (+) to the fungal compartment. Labeling in Arg represented > 90% of the total (15)N in the free AAs of the ERM. [Guanido-2-(15)N]Arg taken up by the ERM and transported to the intra-radical mycelium (IRM) gave rise to (15)N-labeled AAs. [U-(13)C]Arg added to the fungal compartment did not produce any (13)C labeling of other AAs in the mycorrhizal root. Arg is the major form of N synthesized and stored in the ERM and transported to the IRM. However, NH(4) (+) is the most likely form of N transferred to host cells following its generation from Arg breakdown.


Assuntos
Daucus carota/microbiologia , Micorrizas/metabolismo , Nitrogênio/metabolismo , Aminoácidos/metabolismo , Transporte Biológico , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Simbiose
15.
Plant Physiol ; 81(3): 925-8, 1986 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16664927

RESUMO

The uptake of sodium ions by excised corn root tips (Zea mays L. cv FRB-73) was monitored by (23)Na nuclear magnetic resonance (NMR) methods in the presence of a membrane impermeable shift reagent under different metabolic conditions. In addition, for the first time, the energy status as well as the intracellular pH associated with this influx was concurrently evaluated by (31)P NMR. The rate of sodium ion uptake decreased (in order) as the normal metabolic state was changed by the addition of cyanide, anaerobic condition, and carbonyl cyanide trifluoromethoxy phenyl-hydrazone treatment. The results suggest that the proton electrochemical potential of the plasma membrane may facilitate the influx of Na(+).

16.
Plant Physiol ; 81(4): 1130-3, 1986 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16664955

RESUMO

Previous work has shown that undissociated 2,4-dinitrophenol (DNP) both increases the permeability of roots to ions and alters the membrane lipids of barley roots. Anionic DNP is the main entrant form but has no effect on permeability or on the membrane lipids. The amount of anionic DNP taken up by the roots is sufficient, that were it in free solution in the cytoplasm, the DNP would uncouple oxidative phosphorylation, and thereby inhibit ATP synthesis. The present work was undertaken to assess whether DNP alters ATP levels when it is taken up by barley roots. (31)P nuclear magnetic resonance spectra were used to monitor, in vivo, levels of ATP, cytoplasmic phosphate, vacuolar phosphate, and other phosphate compounds in barley roots in the presence of 10 micromolar DNP at pH 5 and pH 7. The spectra indicate that no change in the level of ATP or the cytoplasmic pH occurred in the roots in the presence of DNP for as long as 20 hours. Thus, the effects of undissociated DNP are effects directly on the root membranes and do not involve inhibition of ATP synthesis. Furthermore, the results explain why anionic DNP has no effect on ion uptake and accumulation.

17.
Appl Environ Microbiol ; 58(3): 821-5, 1992 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16348673

RESUMO

Various flavonoids were tested for their ability to stimulate in vitro growth of germinated spores of vesicular-arbuscular mycorrhizal fungi. Experiments were performed in the presence of 2% CO(2), previously demonstrated to be required for growth of Gigaspora margarita (G. Bécard and Y. Piché, Appl. Environ. Microbiol. 55:2320-2325, 1989). Only the flavonols stimulated fungal growth. The flavones, flavanones, and isoflavones tested were generally inhibitory. Quercetin (10 muM) prolonged hyphal growth from germinated spores of G. margarita from 10 to 42 days. An average of more than 500 mm of hyphal growth and 13 auxiliary cells per spore were obtained. Quercetin also stimulated the growth of Glomus etunicatum. The glycosides of quercetin, rutin, and quercitrin were not stimulatory. The axenic growth of G. margarita achieved here under rigorously defined conditions is the most ever reported for a vesicular-arbuscular mycorrhizal fungus.

18.
Anal Biochem ; 243(1): 110-8, 1996 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-8954532

RESUMO

Limits of sensitivity and spectral resolution currently restrict the application of nuclear magnetic resonance (NMR) spectroscopy in plant metabolism. This study shows that these limits can be substantially expanded through the application of heteronuclear single- and multiple-quantum two-dimensional (2D) spectroscopic methods using pulsed field gradients both in vivo and in extracts. The course of metabolism in approximately 0.2 g of maize (Zea mays L.) root tips labeled with [1-13C]glucose was followed with 1 min time resolution using heteronuclear multiple quantum coherence (HMQC) 13C-1H spectroscopy in vivo. The timing of alanine, lactate, and ethanol synthesis was followed during the transition from normal to hypoxic conditions. In extracts of labeled maize root tips, 13C-1H heteronuclear single quantum coherence and heteronuclear multiple quantum coherence (HMBC) spectra acquired in 2-3 h allowed the detection and assignment of resonance that are not seen in one-dimensional (1D) 13C NMR spectra of the same samples taken in 12 h. In root tips labeled with 15NH4+, 15N-(1)H HMQC spectra in vivo showed labeling in the amide of glutamine. In extracts, 15N labeling in amines and amides was detected using 15N-1H HMBC spectra that is not seen in 1D 15N spectra of the same sample.


Assuntos
Plantas/metabolismo , Espectroscopia de Ressonância Magnética/métodos , Zea mays/metabolismo
19.
Biochemistry ; 27(15): 5601-10, 1988 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-3140892

RESUMO

N epsilon-[2H6]Isopropyllysyl-beta-lactoglobulin was prepared by reductive alkylation of beta-lactoglobulin with [2H6]acetone and NaBH4 to provide a 2H (NMR) probe for the study of lysine involvement in lipid-protein interactions. Amino acid analysis showed 80% of the protein's 15 lysine residues to be labeled. Unmodified lysine residues were located through peptide maps produced from CNBr, tryptic, and chymotryptic digests of the labeled protein. Lys47 was not modified; Lys135,138,141, located along an amphipathic helical rod, were each partially unmodified. All other lysine residues were at least 90% modified. Average correlation times calculated from 2H NMR spectra were 20 and 320 ps for 8.7 and 3.3 residues, respectively, in 6 M guanidine hydrochloride; in nondenaturing solution, values of 70 and 320 ps were obtained for 6.5 and 3.2 residues, respectively, with the remaining 2.3 modified residues not observed, suggesting that side chains of lysine residues in unordered or flexible regions were more mobile than those in stable periodic structures. 2H NMR spectra of the protein complexed with dipalmitoylphosphatidylcholine confirmed the extrinsic membrane protein type behavior of beta-lactoglobulin previously reported from 31P NMR studies of the phospholipids complexed with beta-lactoglobulin. Although no physiological function has yet been identified, comparison of these results with the X-ray structure [Papiz et al. (1986) Nature (London) 324, 383-385] supports the hypothesis that residues not accessible for modification may help to stabilize the cone-shaped beta-barrel thought to contain binding sites for small lipid-soluble molecules.


Assuntos
Lactoglobulinas , Lisina , Sequência de Aminoácidos , Animais , Bovinos , Fenômenos Químicos , Química , Cromatografia Líquida de Alta Pressão , Lipossomos , Espectroscopia de Ressonância Magnética , Dados de Sequência Molecular , Movimento (Física) , Fragmentos de Peptídeos/análise , Mapeamento de Peptídeos , Conformação Proteica
20.
Biochem J ; 252(2): 401-8, 1988 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-3415663

RESUMO

Movement of paramagnetic Mn2+ into sycamore (Acer pseudoplatanus) cells has been indirectly examined by observing the line broadening exhibited in its 31P n.m.r. spectra. Mn2+ was observed to pass into the vacuole, while exhibiting a very minor accumulation in the cytoplasm. With time, gradual leakage of phosphate from the vacuole to the cytoplasm was observed along with an increase in glucose-6-phosphate. Anoxia did not appear to affect the relative distribution of Mn2+ in the cytoplasm and vacuole. Under hypoxic conditions restriction of almost all movement of Mn2+ across the plasmalemma as well as the tonoplast was observed. In contrast, maize root tips showed entry and complete complexation of nucleotide triphosphate by Mn2+ during hypoxia. The rate of passage of Mn2+ across the tonoplast in both sycamore and maize root cells is approximately the same. However, the rates of facilitated movement across the respective plasma membranes appear to differ. More rapid movement of Mn2+ across the plasmalemma in maize root tip cells allows a gradual build-up of metal ion in the cytoplasm prior to its diffusion across the tonoplast. Sycamore cells undergo a slower uptake of Mn2+ into their cytoplasms (comparable with the rate of diffusion through the tonoplast), so little or no observable accumulation of Mn2+ is observed in this compartment.


Assuntos
Manganês/farmacocinética , Plantas/metabolismo , Zea mays/metabolismo , Trifosfato de Adenosina/metabolismo , Aerobiose , Transporte Biológico , Citoplasma/metabolismo , Espectroscopia de Ressonância Magnética , Fosfatos/metabolismo , Árvores , Vacúolos/metabolismo
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