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2.
Lupus ; 9(5): 328-32, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-10878723

RESUMO

BACKGROUND: Telomeric hexamer repeats (TTAGGG/CCCTAA)n are highly repetitive sequences of DNA. They cap the termini of eukaryotic chromosomes and stabilize them, preventing degradation or fusion. Anti ds-DNA is one of the most specific tests for systemic lupus erythematosus (SLE). Of related importance, a preliminary report has suggested that anti-telomere antibodies are also highly specific for the presence of SLE. METHODS: 220 patients with SLE, 79 with rheumatoid arthritis (RA), 54 with other rheumatic diseases and 99 healthy controls were tested for anti-telomere antibody as measured by enzyme immunoassay detecting 30- and 60-mer telomeric repeats (5-10 hexamers). 48 of the 220 SLE patients charts were abstracted for 90 separate clinical, laboratory and treatment parameters. Comparisons were made between SLE and non-SLE patients, and within the lupus group for telomere positivity and among the latter 48 patients for anti-DNA (Farr) levels and SLEDAI scores. RESULTS: Anti-telomere antibody was present in 48.6% of the overall SLE group (220), 71% of our cohort (48), 11% with primary Sjogren's (2/18), 7. 6% with RA (6/79) and 2% of normal controls (2/99) (P<0.001 comparing SLE to all other groups). In the 48 patient cohort, anti-telomere antibody was more sensitive than anti-dsDNA (Farr) (71% vs 50%), but did not correlate with other clinical parameters, SLEDAI scores, or other autoantibodies. CONCLUSIONS: The detection of anti-telomere antibody appears to be more sensitive and may be as specific as anti-dsDNA (Farr) in SLE. The detection of telomeric repeats may be as accurate as other anti-DNA assay methodologies and more specific for the presence of SLE. The immunogenic potential of telomere biology related to the pathogenesis and/or diagnosis of SLE deserves further investigation.


Assuntos
Anticorpos Antinucleares/imunologia , Especificidade de Anticorpos , Autoanticorpos/imunologia , Lúpus Eritematoso Sistêmico/imunologia , Telômero/imunologia , Adolescente , Adulto , Idoso , Ensaio de Imunoadsorção Enzimática , Humanos , Lúpus Eritematoso Sistêmico/fisiopatologia , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Prognóstico , Sensibilidade e Especificidade
3.
Lupus ; 9(4): 241-51, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-10866094

RESUMO

OBJECTIVES: The treatment of lupus membranous nephritis (LMN), a lupus subset that carries a high morbidity, is unsatisfactory. We report our experience in treating LMN with the immunosuppressive drug cyclosporine (CYS). METHODS: We treated 10 patients with systemic lupus erythematosus fulfilling ACR criteria with CYS for at least 12 months and followed renal function, serologic activity and SLEDAI scores. PATIENT CHARACTERISTICS: 8 females, 2 males, 50% Caucasian, mean age 37.3 y (range 22-48), disease duration 108.7 months (range 16-216), nephritis duration 35.5 months (range 12-59), date of biopsy to date of starting treatment 10.7 months (range 0-90). The patients were started on CYS with a mean dose of 3.8 mg/kg (range 2.2-6) and followed for a mean duration of 24.8 months (range 12-59). A Medline search identified all patients with lupus who were given CYS or had LMN in articles from 1966-1999. RESULTS: Proteinuria improved from a baseline mean of 5,588mg/24h (range 2,712-11,055) to 1,404 mg/24 h (range < 150-2,652). Serum albumin increased from a baseline mean of 2.8 g/100 ml (range 1.31-3.8) to a mean of 3.9 g/100 ml (range 3-4.5) at last follow-up. There was no significant change in lupus activity as measured by SLEDAI. Nephrotoxicity was common as evidenced by an increase in serum creatinine but it returned to baseline with adjustment of the dose of CYS (20% decrease in the dose of CYS for a 20% increase in serum creatinine). More antihypertensive medications were required to control the blood pressure in these ten patients at the end of the study compared to the onset (total number= 13 versus 6). CONCLUSION: Proteinuria and serum albumin improved in all patients on CYS. A literature review is consistent with this. Controlled studies of the use of CYS for membranous lupus nephritis would be useful.


Assuntos
Ciclosporina/administração & dosagem , Imunossupressores/administração & dosagem , Falência Renal Crônica/tratamento farmacológico , Lúpus Eritematoso Sistêmico/tratamento farmacológico , Nefrite Lúpica/tratamento farmacológico , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Resultado do Tratamento
4.
J Mol Biol ; 294(3): 711-24, 1999 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-10610791

RESUMO

Flavodoxin from Anacystis nidulans (Synechococcus PCC 7942) was the first member of the flavodoxin family to be characterized, and is the structural prototype for the "long-chain" flavodoxins that have molecular masses of approximately 20 kDa. Crystal structure analyses and refinements of three orthorhombic forms of oxidized A. nidulans flavodoxin are reported, and salient features of the fold and the FMN binding site are compared with other flavodoxins. The structure of form I (wild-type: P212121, a=57.08 A, b=69.24 A, c=45.55 A), determined initially by multiple isomorphous replacement, has been refined to R=0.183 and R(free)=0.211 for data from 10.0 to 1.7 A resolution. Structures of form II (wild-type: P212121, a=60.05 A, b=65.85 A, c=51.36 A) and form III (Asn58Gly: P212121, a=51.30 A, b=59.15 A, c=94.44 A) have been determined by molecular replacement and refined versus data to 2.0 A and 1.85 A, respectively; the R values for forms II and III are 0.147 and 0.150. Changes in the molecular contacts that produce the alternative packings in these crystalline forms are analyzed. Deletion of the Asn side-chain in the mutant Asn58Gly removes an intermolecular stacking interaction and allows the alternative packing found in form III crystals. The functionally important 50's loop of the FMN binding site is less restrained by intermolecular contacts in these crystals but maintains the same conformation as in oxidized wild type protein. The structures reported here provide the starting point for structure-function studies of the reduced states and of mutants, described in the accompanying paper.


Assuntos
Cianobactérias/química , Flavodoxina/química , Sequência de Aminoácidos , Sítios de Ligação , Cristalografia por Raios X , Mononucleotídeo de Flavina/metabolismo , Modelos Moleculares , Dados de Sequência Molecular , Oxirredução , Peptídeos/química , Alinhamento de Sequência , Relação Estrutura-Atividade
5.
J Mol Biol ; 294(3): 725-43, 1999 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-10610792

RESUMO

The long-chain flavodoxins, with 169-176 residues, display oxidation-reduction potentials at pH 7 that vary from -50 to -260 mV for the oxidized/semiquinone (ox/sq) equilibrium and are -400 mV or lower for the semiquinone/hydroquinone (sq/hq) equilibrium. To examine the effects of protein interactions and conformation changes on FMN potentials in the long-chain flavodoxin from Anacystis nidulans (Synechococcus PCC 7942), we have determined crystal structures for the semiquinone and hydroquinone forms of the wild-type protein and for the mutant Asn58Gly, and have measured redox potentials and FMN association constants. A peptide near the flavin ring, Asn58-Val59, reorients when the FMN is reduced to the semiquinone form and adopts a conformation ("O-up") in which O 58 hydrogen bonds to the flavin N(5)H; this rearrangement is analogous to changes observed in the flavodoxins from Clostridium beijerinckii and Desulfovibrio vulgaris. On further reduction to the hydroquinone state, the Asn58-Val59 peptide in crystalline wild-type A. nidulans flavodoxin rotates away from the flavin to the "O-down" position characteristic of the oxidized structure. This reversion to the conformation found in the oxidized state is unusual and has not been observed in other flavodoxins. The Asn58Gly mutation, at the site which undergoes conformation changes when FMN is reduced, was expected to stabilize the O-up conformation found in the semiquinone oxidation state. This mutation raises the ox/sq potential by 46 mV to -175 mV and lowers the sq/hq potential by 26 mV to -468 mV. In the hydroquinone form of the Asn58Gly mutant the C-O 58 remains up and hydrogen bonded to N(5)H, as in the fully reduced flavodoxins from C. beijerinckii and D. vulgaris. The redox and structural properties of A. nidulans flavodoxin and the Asn58Gly mutant confirm the importance of interactions made by N(5) or N(5)H in determining potentials, and are consistent with earlier conclusions that conformational energies contribute to the observed potentials.The mutations Asp90Asn and Asp100Asn were designed to probe the effects of electrostatic interactions on the potentials of protein-bound flavin. Replacement of acidic by neutral residues at positions 90 and 100 does not perturb the structure, but has a substantial effect on the sq/hq equilibrium. This potential is increased by 25-41 mV, showing that electrostatic interaction between acidic residues and the flavin decreases the potential for conversion of the neutral semiquinone to the anionic hydroquinone. The potentials and the effects of mutations in A. nidulans flavodoxin are rationalized using a thermodynamic scheme developed for C. beijerinckii flavodoxin.


Assuntos
Cianobactérias/química , Flavodoxina/química , Sequência de Aminoácidos , Sítios de Ligação , Cristalografia por Raios X , Escherichia coli , Mononucleotídeo de Flavina/metabolismo , Flavodoxina/genética , Hidroquinonas/química , Modelos Moleculares , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Oxirredução , Peptídeos/química , Alinhamento de Sequência , Relação Estrutura-Atividade
6.
Lippincotts Prim Care Pract ; 2(1): 52-65, 1998.
Artigo em Inglês | MEDLINE | ID: mdl-9451199

RESUMO

The diagnosis and management of systemic rheumatic disease is predominantly based on clinical parameters. Nevertheless, specific laboratory diagnostic tests may often be critically helpful, for example, in ruling out septic and crystal-induced arthritis in the differential diagnosis of acute monoarthritis. In the evaluation of patients with polyarticular rheumatic disease syndromes, autoimmune testing may be helpful to corroborate the clinical diagnosis of such diverse illnesses as rheumatoid arthritis, systemic lupus erythematosus, Lyme disease, and anticardiolipin syndrome.


Assuntos
Autoanticorpos/análise , Doenças Reumáticas/diagnóstico , Proteínas de Fase Aguda/análise , Anticorpos Antinucleares/análise , Artrite/diagnóstico , Artrite Reumatoide/diagnóstico , Diagnóstico Diferencial , Humanos , Lúpus Eritematoso Sistêmico/diagnóstico
7.
J Clin Apher ; 13(4): 163-6, 1998.
Artigo em Inglês | MEDLINE | ID: mdl-9886795

RESUMO

OBJECTIVE: To assess the efficacy of pulse/synchronization cyclophosphamide/apheresis in patients with proliferative lupus nephritis. METHODS: Eighteen patients with Class III or IV renal biopsies and chronicity indices <6 were prospectively randomized to receive 6 courses of parenteral cyclophosphamide over 8 months along with prednisone. Nine of these patients also received 3 daily plasmaphereses prior to each of the 6 courses of cyclophosphamide. Assessments compiled at 6 and 24 months included serum creatinine, albumin, anti DNA, 24-hour urine protein, and C3 complement along with SLAM scores. RESULTS: Two out of nine patients in each group evolved end stage renal disease and 3/9 patients in each group went into a renal remission at 24 months. Serum albumin, C3 complement, and SLAM scores improved in both groups, and anti-DNA improved in the pulse/synchronization patients (P < 0.025). No intergroup comparisons were significant. CONCLUSION: The addition of pulse/synchronization apheresis to cyclophosphamide therapy does not improve the course of patients with proliferative lupus nephritis.


Assuntos
Remoção de Componentes Sanguíneos/métodos , Ciclofosfamida/administração & dosagem , Imunossupressores/administração & dosagem , Nefrite Lúpica/terapia , Adulto , Divisão Celular/efeitos dos fármacos , Terapia Combinada , Esquema de Medicação , Feminino , Humanos
8.
Biochemistry ; 36(6): 1259-80, 1997 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-9063874

RESUMO

X-ray analyses of wild-type and mutant flavodoxins from Clostridium beijerinckii show that the conformation of the peptide Gly57-Asp58, in a bend near the isoalloxazine ring of FMN, is correlated with the oxidation state of the FMN prosthetic group. The Gly-Asp peptide may adopt any of three conformations: trans O-up, in which the carbonyl oxygen of Gly57 (O57) points toward the flavin ring; trans O-down, in which O57 points away from the flavin; and cis O-down. Interconversions among these conformers that are linked to oxidation-reduction of the flavin can modulate the redox potentials of bound FMN. In the semiquinone and reduced forms of the protein, the Gly57-Asp58 peptide adopts the trans O-up conformation and accepts a hydrogen bond from the flavin N5H [Smith, W. W., Burnett, R. M., Darling, G. D., & Ludwig, M. L. (1977) J. Mol. Biol. 117, 195-225; Ludwig, M. L., & Luschinsky, C. L. (1992) in Chemistry and Biochemistry of Flavoenzymes III (Müller, F., Ed.) pp 427-466, CRC Press, Boca Raton, FL]. Analyses reported in this paper confirm that, in crystals of wild-type oxidized C. beijerinckii flavodoxin, the Gly57-Asp58 peptide adopts the O-down orientation and isomerizes to the cis conformation. This cis form is preferentially stabilized in the crystals by intermolecular hydrogen bonding to Asn137. Structures for the mutant Asn137Ala indicate that a mixture of all three conformers, mostly O-down, exists in oxidized C. beijerinckii flavodoxin in the absence of intermolecular hydrogen bonds. Redox potentials have been manipulated by substitutions that alter the conformational energies of the bend at 56M-G-D-E. The mutation Asp58Pro was constructed to study a case where energies for cis-trans conversion would be different from that of wild type. Intermolecular interactions with Asn137 are precluded in the crystal, yet Gly57-Pro58 is cis, and O-down, when the flavin is oxidized. Reduction of the flavin induces rearrangement to the trans O-up conformation. Redox potential shifts reflect the altered energies associated with the peptide rearrangement; E(ox/sq) decreases by approximately 60 mV (1.3 kcal/mol). Further, the results of mutation of Gly57 agree with predictions that a side chain at residue 57 should make addition of the first electron more difficult, by raising the energy of the O-up conformer that forms when the flavin is reduced to its semiquinone state. The ox/sq potentials in the mutants Gly57Ala, Gly57Asn, and Gly57Asp are all decreased by approximately 60 mV (1.3 kcal/mol). Introduction of the beta-branched threonine side chain at position 57 has much larger effects on the conformations and potentials. The Thr57-Asp58 peptide adopts a trans O-down conformation when the flavin is oxidized; upon reduction to the semiquinone, the 57-58 peptide rotates to a trans O-up conformation resembling that found in the wild-type protein. Changes in FMN-protein interactions and in conformational equilibria in G57T combine to decrease the redox potential for the ox/sq equilibrium by 180 mV (+4.0 kcal/mol) and to increase the sq/hq potential by 80 mV (-1.7 kcal/mol). A thermodynamic scheme is introduced as a framework for rationalizing the properties of wild-type flavodoxin and the effects of the mutations.


Assuntos
Flavodoxina/química , Sequência de Aminoácidos , Clostridium , Cristalografia por Raios X , Mononucleotídeo de Flavina/metabolismo , Flavinas/metabolismo , Flavodoxina/metabolismo , Modelos Moleculares , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Oxirredução , Conformação Proteica , Espectrofotometria Atômica , Espectrofotometria Ultravioleta , Relação Estrutura-Atividade
9.
J Clin Rheumatol ; 2(5): 257-61, 1996 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19078080

RESUMO

The influence of silicone breast implants on patients who develop systemic lupus erythematosus (SLE) and scleroderma are not known. Thirty SLE and 15 scleroderma patients who developed their diseases after under-going augmentation mammoplasty with silicone breast implants were studied. Clinical, laboratory, and treatment features for SLE were compared with age-, sex-, and race-matched controls from our 570-patient cohort. Comparisons were also made with a 75-patient university medical center scleroderma cohort. The SLE implant patients had milder disease but greater frequencies of cutaneous findings, cognitive impairment, and fibromyalgia than SLE patients without implants (p < 0.05). The scleroderma implant group also tended to have milder disease. Of the 45 patients, 26 had their implants removed. Subjective, clinical, and serologic remission after explantation occurred in two of the patients (both with SLE). Twenty-four additional patients had transient subjective improvement or no improvement after explantation; one patient developed malignant hypertension and a scleroderma kidney weeks after explantation.In conclusion, most lupus and scleroderma patients with implants experienced milder, although apparently classical, disease. Dramatic changes in disease course occurred in 3 of the 26 patients immediately after explantation. Because idiopathic disease patients have a 2-10% spontaneous remission rate, more time will be needed to evaluate the natural disease course in the remaining explanted patients.

10.
Semin Arthritis Rheum ; 25(1): 47-55, 1995 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-8525390

RESUMO

Of 500 patients with systemic lupus erythematosus observed at our center, 150 fulfilled criteria for lupus nephritis. Of these 150 patients, 91% were female, and 67% were white. The mean age of onset was 26.2 years, and the mean follow-up duration was 11.7 years. Biopsies (n = 142) performed on 107 patients showed the following World Health Organization (WHO) class distribution: class I, n = 1; class II, n = 13; class III, n = 19; class IV, n = 69; class V, n = 17; class VI, n = 8; and class not determinable, n = 15. Ninety-five patients were nephrotic. Therapeutic intervention courses given to all patients (n = 356) included parenteral (IV) cyclophosphamide (n = 58), high-dose oral steroids (n = 126), pulse steroids (n = 49), apheresis (n = 39), azathioprine (n = 43), oral cyclophosphamide (n = 5), nitrogen mustard (n = 27), and chlorambucil (n = 6). In addition to examining the course of disease for various subsets, various predictors for fatality and end-stage renal disease (ESRD) were analyzed. Descriptive data for the short-term response to five therapies are provided for the complete patient sample, proliferative disease, and nephrotic syndrome. Twenty patients died, primarily from cardiovascular complications and sepsis, with 97% and 92% 5- and 10-year survival rates, respectively. Twenty-nine were dialyzed, and 11 were transplanted. Risk of ESRD by WHO class at 5 years was as follows: class III, 0%; IV, 9%; V, 16% (P = .04 for class V v other patterns).(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Anti-Inflamatórios/uso terapêutico , Imunossupressores/uso terapêutico , Nefrite Lúpica/patologia , Nefrite Lúpica/terapia , Adulto , Anti-Inflamatórios/administração & dosagem , Azatioprina/uso terapêutico , Biópsia , Remoção de Componentes Sanguíneos , Clorambucila/uso terapêutico , Ciclofosfamida/administração & dosagem , Ciclofosfamida/uso terapêutico , Intervalo Livre de Doença , Feminino , Seguimentos , Humanos , Imunossupressores/administração & dosagem , Falência Renal Crônica/etiologia , Nefrite Lúpica/complicações , Nefrite Lúpica/mortalidade , Masculino , Mecloretamina/uso terapêutico , Estudos Retrospectivos , Esteroides , Taxa de Sobrevida , Resultado do Tratamento
13.
Lupus ; 2 Suppl 1: S13-5, 1993 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-8485565

RESUMO

Hydroxychloroquine has several less well-known actions that may have clinical relevance in treating systemic lupus erythematosus (SLE). (1) Hydroxychloroquine has a possible anti-thrombotic action. It is a platelet inhibitor and appears to decrease the risk of thromboembolism in patients with anticardiolipin antibodies. (2) Hydroxychloroquine is associated with lower serum cholesterol and low-density lipoprotein levels compared to those present in patients who are taking corticosteroids but not antimalarials for SLE. (3) It may also decrease abnormal levels of cytokines. Interleukin-6 (IL-6), soluble CD8 and soluble IL-2 receptors (sIL-2R) are lower in patients taking antimalarials compared to those on corticosteroids alone or on neither medication. Serum levels of CD8 and sIL-2R decrease after 6 weeks of hydroxychloroquine treatment. These findings may help explain the favorable response of SLE patients treated with antimalarials.


Assuntos
Antimaláricos/uso terapêutico , Hidroxicloroquina/uso terapêutico , Lúpus Eritematoso Sistêmico/tratamento farmacológico , Animais , Antígenos CD8/sangue , Humanos , Hipercolesterolemia/prevenção & controle , Interleucina-6/sangue , Lúpus Eritematoso Sistêmico/complicações , Lúpus Eritematoso Sistêmico/imunologia , Receptores de Interleucina-2/metabolismo , Tromboembolia/prevenção & controle
15.
Semin Arthritis Rheum ; 21(4): 221-6, 1992 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-1570517

RESUMO

Sixty-seven patients with cutaneous lupus erythematosus (CLE) were followed up as part of a series of 570 lupus erythematosus patients seen in a private practice between 1980 and 1989. Clinical and laboratory features, treatment, and natural course were observed. Findings of interest included (1) a ratio of at least one CLE case for every seven cases of systemic lupus erythematosus (SLE); (2) occurrence of CLE in fewer women and apparently associated with an older age at diagnosis than SLE; (3) similar frequency of cutaneous lupus subsets in CLE and SLE; (4) strong family history for SLE but not CLE in CLE patients; (5) other cutaneous and musculoskeletal features in a majority of CLE patients and constitutional symptoms in 10%; (6) positive ANA titers, high sedimentation rates, and leukopenia common in CLE; (7) anticardiolipin antibody in 31% of CLE patients but not associated with systemic complications; (8) antimalarials required by 75% of patients and systemic steroids by 33%; and (9) an excellent prognosis associated with CLE, organ-threatening disease being rare.


Assuntos
Lúpus Eritematoso Cutâneo , Lúpus Eritematoso Sistêmico , Adulto , Anticorpos/análise , Cardiolipinas/imunologia , Feminino , Humanos , Lúpus Eritematoso Cutâneo/sangue , Lúpus Eritematoso Sistêmico/sangue , Masculino , Prognóstico
16.
Semin Arthritis Rheum ; 21(1): 55-64, 1991 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-1948102

RESUMO

Five hundred seventy lupus erythematosus patients observed in a private practice between 1980 and 1989 were surveyed. Fifty-five percent were diagnosed after 1980. Five hundred three fulfilled criteria for systemic lupus erythematosus ( [SLE]; 464 idiopathic, 23 overlap, 16 drug-induced) and 67 had biopsy-documented cutaneous (discoid) lupus. In the idiopathic SLE group, symptoms began at a mean age of 31 years and patients were observed for a mean of 6 years. Findings in idiopathic SLE patients were (1) 27% have a family history of autoimmune disease; (2) nephritis patients without nephrotic syndrome rarely develop renal failure (4%); (3) nephrotic syndrome patients are relatively cyclophosphamide-resistant; (4) organ-threatening disease is present in 54%; and (5) 13% of women who become pregnant are recurrent aborters and 26% never conceive. In an analysis of cohort data, 5- and 10-year survivals were 97% +/- 2% and 93% +/- 3%, respectively. Additionally, men and patients with renal disease or thrombocytopenia had a poorer prognosis. Blacks had similar clinical findings and survival to whites. Approximately 50% of deaths were from active disease and 50% from complications of therapy. Prolonged survival has resulted from new diagnostic procedures and serologic tests, and improved antibiotics and antihypertensive agents, as well as more efficacious treatment modalities.


Assuntos
Lúpus Eritematoso Sistêmico , Adolescente , Adulto , Fatores Etários , Doenças Autoimunes/genética , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Humanos , Lactente , Recém-Nascido , Lúpus Eritematoso Sistêmico/epidemiologia , Lúpus Eritematoso Sistêmico/mortalidade , Lúpus Eritematoso Sistêmico/fisiopatologia , Masculino , Pessoa de Meia-Idade , Gravidez , Complicações na Gravidez , Grupos Raciais , Fatores Sexuais , Análise de Sobrevida
17.
J Mol Biol ; 219(2): 335-58, 1991 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-2038060

RESUMO

The structure of Mn(III) superoxide dismutase (Mn(III)SOD) from Thermus thermophilus, a tetramer of chains 203 residues in length, has been refined by restrained least-squares methods. The R-factor [formula: see text] for the 54,056 unique reflections measured between 10.0 and 1.8 A (96% of all possible reflections) is 0.176 for a model comprising the protein dimer and 180 bound solvents, the asymmetric unit of the P4(1)2(1)2 cell. The monomer chain forms two domains as determined by distance plots: the N-terminal domain is dominated by two long antiparallel helices (residues 21 to 45 and 69 to 89) and the C-terminal domain (residues 100 to 203) is an alpha + beta structure including a three-stranded sheet. Features that may be important for the folding and function of this MnSOD include: (1) a cis-proline in a turn preceding the first long helix; (2) a residue inserted at position 30 that distorts the helix near the first Mn ligand; and (3) the locations of glycine and proline residues in the domain connector (residues 92 to 99) and in the vicinity of the short cross connection (residues 150 to 159) that links two strands of the beta-sheet. Domain-domain contacts include salt bridges between arginine residues and acidic side chains, an extensive hydrophobic interface, and at least ten hydrogen-bonded interactions. The tetramer possesses 222 symmetry but is held together by only two types of interfaces. The dimer interface at the non-crystallographic dyad is extensive (1000 A2 buried surface/monomer) and incorporates 17 trapped or structural solvents. The dimer interface at the crystallographic dyad buries fewer residues (750 A2/monomer) and resembles a snap fastener in which a type I turn thrusts into a hydrophobic basket formed by a ring of helices in the opposing chain. Each of the metal sites is fully occupied, with the Mn(III) five-co-ordinate in trigonal bipyramidal geometry. One of the axial ligands is solvent; the four protein ligands are His28, His83, Asp166 and His170. Surrounding the metal-ligand cluster is a shell of predominantly hydrophobic residues from both chains of the asymmetric unit (Phe86A, Trp87A, Trp132A, Trp168A, Tyr183A, Tyr172B, Tyr173B), and both chains collaborate in the formation of a solvent-lined channel that terminates at Tyr36 and His32 near the metal ion and is presumed to be the path by which substrate or other inner-sphere ligands reach the metal.(ABSTRACT TRUNCATED AT 400 WORDS)


Assuntos
Superóxido Dismutase/química , Thermus/enzimologia , Sequência de Aminoácidos , Animais , Humanos , Substâncias Macromoleculares , Modelos Moleculares , Dados de Sequência Molecular , Conformação Proteica , Homologia de Sequência do Ácido Nucleico , Superóxido Dismutase/genética , Difração de Raios X/métodos
18.
Free Radic Res Commun ; 12-13 Pt 1: 259-68, 1991.
Artigo em Inglês | MEDLINE | ID: mdl-2071033

RESUMO

Using the complete sequences for MnSOD from Thermus thermophilus and for FeSOD from E. coli, structural models for both oxidized enzymes have been refined, the Mn protein to an R of 0.186 for all data between 10.0 and 1.8 A, and the Fe protein to an R of 0.22 for data between 10.0 and 2.5 A. The results of the refinements support the presence of a solvent as a fifth ligand to Mn(III) and Fe(III) and a coordination geometry that is close to trigonal bipyramidal. The putative substrate-entry channel is comprised of residues from both subunits of the dimer; several basic residues that are conserved may facilitate approach of O2-, while other conserved residues maintain interchain packing interactions. Analysis of the azide complex of Fe(III) dismutase suggests that during turnover O2- binds to the metal at a sixth coordination site without displacing the solvent ligand. Because crystals reduced with dithionite show no evidence for displacement of the protein ligands, the redox-linked proton acceptor (C. Bull and J.A. Fee (1985), Journal of the American Chemistry Society 107, 3295-3304) is unlikely to be one of the histidines which bind the metal ion. Structural, kinetic, titration, and spectroscopic data can be accommodated in a mechanistic scheme which accounts for the differential titration behaviour of the Fe(III) and Fe(II) enzymes at neutral and high pH.


Assuntos
Proteínas de Bactérias/química , Superóxido Dismutase/química , Sequência de Aminoácidos , Proteínas de Bactérias/antagonistas & inibidores , Sítios de Ligação , Escherichia coli/enzimologia , Ferro , Manganês , Modelos Moleculares , Dados de Sequência Molecular , Ligação Proteica , Conformação Proteica , Relação Estrutura-Atividade , Superóxido Dismutase/antagonistas & inibidores , Thermus/enzimologia
19.
Biochemistry ; 29(45): 10364-75, 1990 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-2261478

RESUMO

Flavodoxins from Clostridium beijerinckii and from Megasphaera elsdenii with 1-carba-1-deaza-FMN substituted for FMN have been used to study flavin-protein interactions in flavodoxins. The oxidized 1-deaza analogue of FMN binds to apoflavodoxins from M. elsdenii and C. beijerinckii (a.k.a. Clostridium MP) with association constants (Ka) of 1.0 x 10(7) M-1 and 3.1 x 10(6) M-1, values about 10(2) less than the corresponding Ka values for FMN. X-ray structure analysis of oxidized 1-deaza-FMN flavodoxin from C. beijerinckii at 2.5-A resolution shows that the analogue binds with the flavin atoms in the same locations as their equivalents in FMN but that the protein moves in the vicinity of Gly 89 to accommodate the 1-CH group, undergoing displacements which increase the distance between position 1 of the flavin ring and the main-chain atoms of Gly 89 and move the peptide hydrogen of Gly 89 by about 0.6 A. The X-ray analysis implies that protonation of normal flavin at N(1), as would occur in formation of the neutral fully reduced species, would result in a similar structural perturbation. The oxidation-reduction potentials of 1-deaza-FMN flavodoxin from M. elsdenii have been determined in the pH range 4.5-9.2. The oxidized/semiquinone equilibrium (E'0 = -160 mV at pH 7.0) displays a pH dependence of -60 mV per pH unit; the semiquinone/reduced equilibrium (E'0 = -400 mV at pH 7.0) displays a pH dependence of -60 mV per pH unit at low pH and is pH independent at high pH, with a redox-linked pK of 7.4. Spectral changes of fully reduced 1-deaza-FMN flavodoxin with pH suggest that this latter pK corresponds to protonation of the flavin ring system (the pK of free reduced 1-deaza-FMN is 5.6 [Spencer, R., Fisher, J., & Walsh, C. (1977) Biochemistry 16, 3586-3593]. The pK of reduced 1-deaza-FMN flavodoxin provides an estimate of the electrostatic interaction between the protein and the bound prosthetic group; the free energy of binding neutral reduced 1-deaza-FMN is more negative than that for binding the anionic reduced 1-deaza-FMN by 2.4 kcal.(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Mononucleotídeo de Flavina/metabolismo , Flavodoxina/metabolismo , Clostridium/análise , Mononucleotídeo de Flavina/química , Flavinas/metabolismo , Flavodoxina/química , Concentração de Íons de Hidrogênio , Oxirredução , Conformação Proteica , Termodinâmica , Difração de Raios X
20.
Am J Med ; 89(3): 322-6, 1990 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-2393036

RESUMO

PURPOSE: The effects of hydroxychloroquine (HCQ) on serum levels of cholesterol, triglycerides, and high- (HDL) and low-density lipoprotein (LDL) were studied in patients with rheumatoid arthritis or systemic lupus erythematosus. PATIENTS AND METHODS: A total of 155 women were divided into the following treatment groups: Group A: patients taking HCQ and no steroids (n = 58); Group B: patients taking steroids and no HCQ (n = 35); Group C: patients receiving both HCQ and steroids (n = 18); and Group D: patients receiving neither HCQ nor steroids (n = 44). RESULTS: HCQ therapy had a high statistical association with low serum levels of cholesterol (181 mg/dL; p = 0.0006), triglycerides (106 mg/dL; p = 0.0459), and LDL (101 mg/dL; p = 0.0004), irrespective of concomitant steroid administration. The HCQ-treated group (A) had lower cholesterol (181 mg/dL; p = 0.0039) and LDL (101 mg/dL; p = 0.007) levels than those receiving neither HCQ nor steroids (205 mg/dL) and 128 mg/dL) (Group D). No HDL differences were observed. CONCLUSION: The effects of HCQ do not appear to be due to changes in diet or weight, and the drug was well tolerated. Although the mechanism of cholesterol lowering by HCQ is not known, this drug deserves further investigation for its lipid-lowering properties.


Assuntos
Corticosteroides/efeitos adversos , Artrite Reumatoide/tratamento farmacológico , Colesterol/sangue , Hidroxicloroquina/uso terapêutico , Hipolipemiantes , Lúpus Eritematoso Sistêmico/tratamento farmacológico , Adolescente , Adulto , Idoso , Artrite Reumatoide/sangue , HDL-Colesterol/sangue , LDL-Colesterol/sangue , Feminino , Humanos , Lúpus Eritematoso Sistêmico/sangue , Pessoa de Meia-Idade , Triglicerídeos/sangue
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