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1.
Br J Dermatol ; 180(2): 397-403, 2019 02.
Artículo en Inglés | MEDLINE | ID: mdl-30269346

RESUMEN

BACKGROUND: Alexithymia refers to difficulty in identifying and expressing emotions. Alexithymia is associated with high burden of disease in patients with psoriasis. OBJECTIVES: To investigate whether alexithymia was reversible in patients with psoriasis following real-life therapeutic intervention. METHODS: The Epidemiological Study in Patients with Recently Diagnosed Psoriasis (EPIDEPSO; NCT01964443) was a 1-year multicentre observational study investigating the prevalence of alexithymia and other psychosocial comorbidities in patients with psoriasis with ≤ 10 years' disease duration and eligible for systemic treatment. Alexithymia was assessed using the Toronto Alexithymia Scale (TAS-20) at baseline, 6 months and 1 year. RESULTS: There was a statistically significant decrease in the prevalence of alexithymia in the follow-up cohort, from 26·7% at baseline to 21·2% at 6 months and 18·8% at 1 year. More than half of the patients (n = 77, 53·8%) who were alexithymic at baseline experienced reversion of their alexithymia. Reversion of alexithymia was higher in patients who reached a high level of disease control, defined as ≥ 75% or ≥ 90% improvement in Psoriasis Area and Severity Index. Reversion of alexithymia was associated with dramatic improvement in quality of life, anxiety and depression. Moreover, hazardous alcohol use, highly prevalent in patients with alexithymia, was reduced almost threefold at 1 year. CONCLUSIONS: Alexithymia and associated high disease burden may be reversible in patients with effective treatment of psoriasis. Proactive recognition of patients who are unable to identify and express their feelings is important.


Asunto(s)
Síntomas Afectivos/epidemiología , Costo de Enfermedad , Fármacos Dermatológicos/uso terapéutico , Psoriasis/tratamiento farmacológico , Calidad de Vida , Adulto , Síntomas Afectivos/diagnóstico , Síntomas Afectivos/psicología , Ansiedad/diagnóstico , Ansiedad/epidemiología , Ansiedad/psicología , Comorbilidad , Depresión/diagnóstico , Depresión/epidemiología , Depresión/psicología , Femenino , Estudios de Seguimiento , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Medición de Resultados Informados por el Paciente , Prevalencia , Psoriasis/diagnóstico , Psoriasis/epidemiología , Psoriasis/psicología , Pruebas Psicológicas/estadística & datos numéricos , Autoinforme/estadística & datos numéricos , Índice de Severidad de la Enfermedad , Resultado del Tratamiento , Adulto Joven
2.
Br J Dermatol ; 176(5): 1195-1203, 2017 05.
Artículo en Inglés | MEDLINE | ID: mdl-27995617

RESUMEN

BACKGROUND: Single-centre studies show that alexithymia, defined as difficulty in recognizing and describing emotions, is more prevalent among patients with psoriasis than in the general population. However, its prevalence and the consequences of the association between alexithymia and psoriasis are unclear. OBJECTIVES: The primary objective of this study was to determine the prevalence of alexithymia, as defined by a score ≥ 61 in the 20-item Toronto Alexithymia Scale, in a large sample of patients who had plaque psoriasis for ≤ 10 years and were eligible for phototherapy or systemic treatment. The secondary objectives were to investigate the relationship between alexithymia and the clinical and psychological aspects of psoriasis. METHODS: Data were collected in the framework of an observational, multicentre, international study, the EPidemiological Study In Patients With Recently DiagnosEd PSOriasis (EPIDEPSO), aiming at investigating the prevalence of alexithymia and other psychosocial comorbidities in patients with psoriasis of ≤ 10 years' disease duration. RESULTS: The prevalence of alexithymia within a cohort of 670 patients was 24·8% (95% confidence interval 21·7-28·2). Patients with alexithymia had a higher burden of psoriasis, including significant impairment of quality of life, higher levels of anxiety and depression, a higher risk of alcohol dependency and impairment of work productivity, compared with patients without alexithymia. CONCLUSIONS: It is important to identify alexithymic patients with psoriasis in clinical practice as they experience a higher disease burden and have a lower ability to express their feelings.


Asunto(s)
Síntomas Afectivos/etiología , Costo de Enfermedad , Psoriasis/psicología , Adulto , Síntomas Afectivos/epidemiología , Estudios de Casos y Controles , Europa (Continente)/epidemiología , Femenino , Humanos , Masculino , Prevalencia , Psoriasis/epidemiología , Escalas de Valoración Psiquiátrica , Calidad de Vida , Factores de Riesgo , Índice de Severidad de la Enfermedad , Sudáfrica/epidemiología
3.
Acta Crystallogr D Biol Crystallogr ; 70(Pt 6): 1640-8, 2014 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-24914975

RESUMEN

Neuroglobin is a member of the globin family involved in neuroprotection; it is primarily expressed in the brain and retina of vertebrates. Neuroglobin belongs to the heterogeneous group of hexacoordinate globins that have evolved in animals, plants and bacteria, endowed with the capability of reversible intramolecular coordination, allowing the binding of small gaseous ligands (O2, NO and CO). In a unique fashion among haemoproteins, ligand-binding events in neuroglobin are dependent on the sliding of the haem itself within a preformed internal cavity, as revealed by the crystal structure of its CO-bound derivative. Point mutants of the neuroglobin internal cavity have been engineered and their functional and structural characterization shows that hindering the haem displacement leads to a decrease in CO affinity, whereas reducing the cavity volume without interfering with haem sliding has negligible functional effects.


Asunto(s)
Globinas/química , Hemo/química , Proteínas del Tejido Nervioso/química , Monóxido de Carbono/química , Cristalografía por Rayos X , Globinas/genética , Cinética , Modelos Moleculares , Mutación , Proteínas del Tejido Nervioso/genética , Neuroglobina , Ingeniería de Proteínas
4.
Br J Dermatol ; 170(2): 435-44, 2014 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-24116868

RESUMEN

BACKGROUND: There are limited long-term, 'real-world' data on ustekinumab, or the effect of dose adjustment in suboptimal responders. OBJECTIVES: We describe 52-week data from TRANSIT, which initiated ustekinumab by licensed regimen and investigated exploratory dose adjustment. METHODS: Patients with moderate-to-severe psoriasis and inadequate methotrexate response received ustekinumab, with immediate or gradual methotrexate withdrawal. Outcomes were similar between treatment arms at week 12 (primary endpoint), so week 52 data were pooled. Patients weighing ≤ 100 kg or > 100 kg were administered ustekinumab 45 or 90 mg, respectively. Patients weighing ≤ 100 kg without 75% improvement in Psoriasis Area and Severity Index (PASI 75) response at weeks 28 or 40 received a dose adjustment to 90 mg. The primary analysis used observed data. RESULTS: Overall, 391 and 98 patients received ustekinumab 45 and 90 mg, respectively. Forty-four patients (9%) discontinued before week 52 (0·4% due to adverse events). At week 52 (in the overall population), 369 patients (83%) achieved a PASI score ≤ 5, and 341 patients (77%) achieved PASI 75; the median PASI score decreased from 15 at baseline to 1·8. At weeks 28 and 40, 84 and 31 patients, respectively, did not achieve PASI 75 and received a dose adjustment; by week 52, 35/82 (43%) and 15/31 (48%) of these patients, respectively, achieved PASI 75 (two discontinued between weeks 28 and 40). CONCLUSIONS: Ustekinumab showed sustained 1-year efficacy and was well tolerated when initially administered according to label. Adjusting the ustekinumab dose to 90 mg may result in clinically meaningful improvement in response in patients weighing ≤ 100 kg with suboptimal initial response.


Asunto(s)
Anticuerpos Monoclonales Humanizados/administración & dosificación , Fármacos Dermatológicos/administración & dosificación , Metotrexato/administración & dosificación , Psoriasis/tratamiento farmacológico , Anticuerpos Monoclonales Humanizados/efectos adversos , Fármacos Dermatológicos/efectos adversos , Relación Dosis-Respuesta a Droga , Método Doble Ciego , Sustitución de Medicamentos , Femenino , Humanos , Masculino , Metotrexato/efectos adversos , Persona de Mediana Edad , Resultado del Tratamiento , Ustekinumab
5.
Nat Med ; 3(5): 521-5, 1997 May.
Artículo en Inglés | MEDLINE | ID: mdl-9142120

RESUMEN

A characteristic feature of Creutzfeldt-Jakob disease (CJD) is the accumulation in the brain of the amyloid protease-resistant protein PrPres. PrPres derives from a host-encoded, protease-sensitive isoform, PrPsen. Mutations of this protein are linked to familial variants of the disease, and the presence of a methionine or valine residue at the polymorphic position 129 may be critical in sporadic CJD cases. We found that in the brain of patients heterozygous for the mutation in which isoleucine is substituted for valine at codon 210 (Val21Olle), the PrPres is formed by both the wild-type and mutant PrPsen. We also found that in a sporadic CJD patient, who was heterozygous (Met/Val) at position 129, PrPres is also formed by both allotypes. These data associate transmissible spongiform encephalopathies with other amyloidosis, although the nature of the transmissible agent remains unsettled.


Asunto(s)
Química Encefálica , Síndrome de Creutzfeldt-Jakob/genética , Mutación/genética , Proteína PrP 27-30/genética , Secuencia de Aminoácidos , Animales , Codón/genética , Síndrome de Creutzfeldt-Jakob/metabolismo , Cricetinae , Heterocigoto , Humanos , Mesocricetus , Datos de Secuencia Molecular , Polimorfismo Genético , Proteína PrP 27-30/análisis , Proteína PrP 27-30/aislamiento & purificación , Análisis de Secuencia
6.
Trends Biochem Sci ; 26(1): 21-3, 2001 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-11165512

RESUMEN

Myoglobin, the monomeric haemoprotein expressed in red muscle, is reported in biochemistry and physiology textbooks to function as an intracellular oxygen carrier and oxygen reservoir. Here, Maurizio Brunori argues that myoglobin can also play the role of intracellular scavenger of nitric oxide, an inhibitor of mitochondrial cytochrome-c oxidase, thereby protecting respiration in the skeletal muscle and the heart.


Asunto(s)
Complejo IV de Transporte de Electrones/metabolismo , Músculo Esquelético/metabolismo , Miocardio/metabolismo , Mioglobina/metabolismo , Óxido Nítrico/metabolismo , Animales , Respiración de la Célula/fisiología
7.
Trends Biochem Sci ; 26(4): 209-10, 2001 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-11295538

RESUMEN

It has been proposed that myoglobin (Mb), besides being an oxygen carrier, plays the role of a nitric oxide (NO) scavenger in heart and skeletal muscle. A paper reporting data obtained using perfused hearts isolated from either wild-type or Mb-knockout mice provides the first experimental evidence for this novel function of Mb. The biochemical basis underlying the effects of NO on cardiac function is outlined in this article, beginning with the idea that this gas is an inhibitor of cytochrome-c oxidase. Some of the consequences of this new role of Mb and a molecular mechanism to account for the high reactivity of oxymyoglobin with NO are also briefly discussed.


Asunto(s)
Mioglobina/fisiología , Óxido Nítrico/fisiología , Animales , Complejo IV de Transporte de Electrones/antagonistas & inhibidores , Corazón/fisiología , Ratones , Ratones Noqueados , Músculo Esquelético/enzimología , Músculo Esquelético/fisiología , Mioglobina/genética , Óxido Nítrico/metabolismo
8.
Methods Enzymol ; 437: 397-416, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18433639

RESUMEN

Protein structure is endowed with a complex dynamic nature, which rules function and controls activity. The experimental investigations that yield information on protein dynamics are carried out in solution; however, in most cases, the determination of protein structure is carried out by crystallography that relies on the diffraction properties of a large number of molecules, in approximately the same conformation, arranged in a three-dimensional lattice. Myoglobin, maybe the most thoroughly characterized protein, has allowed the formulation of general principles in the field of protein structure-function correlation and, since the late 1990s, it has been possible to obtain directly some insight into the complex dynamic behavior of myoglobin and other proteins by Laue diffraction. This chapter describes some of the technological features involved in obtaining reliable data by time-resolved Laue crystallography, with subnanosecond time resolution. A synopsis of the more significant findings obtained by laser photolysis of myoglobin-CO crystals is also presented, emphasizing the more general aspects of dynamics relevant to the complex energy landscape of a protein.


Asunto(s)
Mioglobina/química , Cristalografía por Rayos X/métodos , Cinética , Modelos Biológicos , Modelos Moleculares , Fotólisis , Conformación Proteica , Manejo de Especímenes , Factores de Tiempo
9.
Oncogene ; 25(7): 990-7, 2006 Feb 16.
Artículo en Inglés | MEDLINE | ID: mdl-16205637

RESUMEN

Although telomere instability is observed in human tumors and is associated with the development of cancers in mice, it has yet to be established that it can contribute to the malignant transformation of human cells. We show here that in checkpoint-compromised telomerase-positive human fibroblasts an episode of TRF2 inhibition promotes heritable changes that increase the ability to grow in soft agar, but not tumor growth in nude mice. This transforming activity is associated to a burst of telomere instability but is independent of an altered control of telomere length. Moreover, it cannot be recapitulated by an increase in chromosome breaks induced by an exposure to gamma-radiations. Since it can be revealed in the context of telomerase-proficient human cells, telomere dysfunction might contribute to cancer progression even at late stages of the oncogenesis process, after the telomerase reactivation step.


Asunto(s)
Transformación Celular Neoplásica/metabolismo , Fibroblastos/enzimología , Fibroblastos/patología , Telomerasa/metabolismo , Proteína 2 de Unión a Repeticiones Teloméricas/antagonistas & inhibidores , Alelos , Animales , Línea Celular Transformada , Transformación Celular Neoplásica/genética , Femenino , Humanos , Ratones , Ratones Desnudos , Mutación , Virus 40 de los Simios/genética , Proteína 2 de Unión a Repeticiones Teloméricas/genética , Proteína 2 de Unión a Repeticiones Teloméricas/metabolismo , Transfección
10.
Curr Biol ; 5(5): 462-5, 1995 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-7583088

RESUMEN

The recent transplantation of an unusual allosteric effect from crocodile to human haemoglobin has implications for both molecular evolution and the engineering of artificial blood substitutes.


Asunto(s)
Ingeniería Genética , Hemoglobinas , Caimanes y Cocodrilos , Regulación Alostérica , Animales , Evolución Biológica , Sustitutos Sanguíneos/química , Hemoglobinas/química , Hemoglobinas/genética , Humanos , Estructura Molecular
11.
FASEB J ; 20(13): 2192-7, 2006 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-17077295

RESUMEN

The discovery that a myoglobin-like hemeprotein (called neuroglobin) is expressed in our brain raised considerable curiosity from the standpoints of biochemistry and pathophysiology alike. Neuroglobin is involved in neuroprotection from damage due to hypoxia or ischemia in vitro and in vivo; overexpression of neuroglobin ameliorates the recovery from stroke in experimental animals. The mechanism underlying this remarkable effect is still mysterious. Structural studies revealed that neuroglobin has a typical globin fold, and despite being hexacoordinated, it binds reversibly O2, CO, and NO, undergoing a substantial conformational change of the heme and of the protein. The possible mechanisms involved in neuroprotection are briefly reviewed. Neuroglobin is unlikely to be involved in O2 transport (like myoglobin), although it seems to act as a sensor of the O2/NO ratio in the cell, possibly regulating the GDP/GTP exchange rate forming a specific complex with the G(alpha beta gamma)-protein when oxidized but not when bound to a gaseous ligand. Thus it appears that neuroglobin is a stress-responsive sensor for signal transduction in the brain, mediated by a ligand-linked conformational change of the protein.


Asunto(s)
Encéfalo/fisiología , Globinas/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Animales , Transporte Biológico , Globinas/química , Humanos , Ligandos , Ratones , Proteínas del Tejido Nervioso/química , Neuroglía/fisiología , Neuroglobina , Neuronas/fisiología , Oxígeno/metabolismo , Conformación Proteica , Pliegue de Proteína
12.
Clin Ter ; 158(1): 11-6, 2007.
Artículo en Italiano | MEDLINE | ID: mdl-17405654

RESUMEN

OBJECTIVE: To evaluate whether long-term Non-Invasive Mechanical Ventilation (NIMV) might have an effect on respiratory drive and respiratory muscles strength, measuring mouth occlusion pressure (P0,) and maximal inspiratory pressure (MIP). PATIENTS AND METHODS: 20 consecutive patients with hypercapnic respiratory failure underwent measurements of dyspnea, respiratory drive and respiratory muscles strength before hospital treatment with NIMV; those patients who showed significant improvement of gas-exchange continued home ventilation for a period of four weeks, and were readmitted to hospital for re-evaluation of Borg's scale for dyspnea, P0,1 and MIP. RESULTS: Data obtained show a mild reduction of P0,1 and a significant improvement of respiratory muscles strength, with satisfactory dyspnea relief. CONCLUSIONS: We conclude that unloading respiratory muscles through mechanical ventilation results in better muscle performance in the long-term that could act, together with normalization of gas-exchange, on neuromuscular respiratory drive and contribute to dyspnea relief.


Asunto(s)
Disnea/terapia , Servicios de Atención de Salud a Domicilio , Hipercapnia/terapia , Respiración Artificial/métodos , Insuficiencia Respiratoria/terapia , Mecánica Respiratoria/fisiología , Músculos Respiratorios/fisiología , Anciano , Anciano de 80 o más Años , Análisis de los Gases de la Sangre , Disnea/diagnóstico , Femenino , Humanos , Capacidad Inspiratoria/fisiología , Masculino , Ventilación Voluntaria Máxima/fisiología , Persona de Mediana Edad , Oxígeno/sangre , Intercambio Gaseoso Pulmonar , Factores de Tiempo
13.
Clin Ter ; 158(2): 115-20, 2007.
Artículo en Italiano | MEDLINE | ID: mdl-17566511

RESUMEN

OBJECTIVE: To contribute to an early diagnosis of pulmonary involvement in scleroderma by evaluating the correlation between respiratory symptoms and functional respiratory data observed. PATIENTS AND METHODS: 86 patients affected by scleroderma, 76 women and 10 men, age 14-75, underwent lung function tests, blood gas sample, CO diffusing capacity in setting and supine position, respiratory drive measurement through P0.1 and evaluation of the respiratory muscles efficiency with Maximum Inspiratory Pressure (MIP). RESULTS: Data obtained suggested us to divide our patients in four different groups: first group where both spirometric data and pulmonary diffusion were normal; a second group with a clear reduction of pulmonary diffusion likely due to the reduction of vascular bed; a third group where we observed a restrictive ventilatory impairment due to the reduction of the compliance and a reduction of the pulmonary diffusion likely related to interstitial damage; finally, a fourth group where beside a restricted spirometric outline we have detected a more accentuated reduction of pulmonary diffusion likely due to pulmonary hypertension. Moreover, our study has highlighted a progressive decrease of MIP and Maximum Voluntary Ventilation (MVV) shifting from the first to the fourth group, suggesting reduction of the muscular efficiency with an increase of P0.1 index of activity in the respiratory drive. CONCLUSIONS: The results could explain the dyspnea often reported by the patients affected by scleroderma even without spirometric alteration.


Asunto(s)
Esclerodermia Sistémica/fisiopatología , Adolescente , Adulto , Anciano , Análisis Químico de la Sangre , Femenino , Humanos , Masculino , Persona de Mediana Edad , Esclerodermia Sistémica/sangre , Espirometría
14.
Leuk Lymphoma ; 47(6): 1091-102, 2006 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-16840201

RESUMEN

Post-remission therapy in acute myeloid leukemia (AML) remains problematic. It has been demonstrated that younger patients can maintain longer complete remissions (CR) with aggressive post-remission therapies after induction treatment: allogeneic (allo), autologous (auto) stem cell transplantation (SCT), or intensive chemotherapy (ICC). The purpose of our study was to identify the most important randomized and controlled studies comparing these three therapeutic options, in order to draw conclusions and possible suggestions for post-remission therapy of AML, according to the evidence based medicine (EBM) rules. We performed an exhaustive analysis of the literature, searching either in electronic databases or among the references of the identified articles (hand searching). We searched the MEDLINE computer database for reports from 1985 through January 2005 and selected for analysis the clinical trials conducted over adults affected by newly diagnosed AML aged less than 65 years. The study design had to satisfy strict methodological criteria and must consider global mortality and/or disease free survival as primary outcomes. Overall we found 7750 papers; by using the limits "clinical trial" as publication type, "all adults 19+ years", we were able to select 344 papers. Among these, a further selection was made, based on two main clinical queries: 1) is auto-SCT superior to ICC/no other therapy in improving DFS and/or OS in adult AML patients in first CR? 2) is allo-SCT superior to auto-SCT/other therapeutic options in improving DFS and/or OS in adult AML patients in first CR? Concerning the first query, a possible advantage of auto-SCT over ICC was not clearly supported by data from clinical trials; there is no evidence that auto-SCT is superior in terms of OS to chemotherapy. Nevertheless, the reported TRM has been significantly reduced within the past years. Thus, the percentage of patients suitable for auto-SCT in CR has increased. Moreover, the scarce data concerning the comparison between auto-SCT and chemotherapy in different subsets of patients are unable to suggest a differentiated approach in patients with high-risk, standard-risk or low-risk AML. Data from the literature show that patients with unfavorable risk disease are more often addressed to allo-SCT and patients with low-risk disease receive more often intensive consolidation chemotherapy. Concerning the second query, interpretation of data from the main prospective studies about the role of allo-SCT in previously untreated AML is not easy. The first problem is the lack of real randomized clinical trials; in fact, according to the reported studies, AML patients generally receive allo-SCT on the basis of donor availability (the so called "genetic randomization"). The second problem is the frequent absence of intention to treat analysis. Despite methodological limitations, it was possible to compare allo-SCT with auto-SCT on a donor versus no-donor analysis and within risk groups. No overall benefit of allo-grafting on survival was demonstrated by any trial. In conclusion, the EBM approach highlighted the limitations observed in the published studies concerning consolidation therapy in AML; some suggestions, emerging from non-randomized, as well as randomized studies, are adequate, but not conclusive. This point, coupled with the intrinsic complexity to study AML biological heterogeneity, is probably a major obstacle to draw conclusive evidences for consolidation therapy in AML. These observations should plan to address new randomized studies on AML therapy; however, due to the emergence of genetic subgroups and new drugs targeting specific abnormalities, these trials should probably be designed directly focusing on the single entities. In this way, the cure of AML could eventually become the cure of each specific AML subset with its peculiar biological, molecular and prognostic features.


Asunto(s)
Medicina Basada en la Evidencia , Leucemia Mieloide Aguda/tratamiento farmacológico , Trasplante de Células Madre/métodos , Adulto , Factores de Edad , Antineoplásicos/farmacología , Ensayos Clínicos como Asunto/métodos , Supervivencia sin Enfermedad , Humanos , Inducción de Remisión , Proyectos de Investigación , Trasplante Homólogo , Resultado del Tratamiento
15.
Structure ; 5(9): 1157-71, 1997 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-9331415

RESUMEN

BACKGROUND: Nitrite reductase from Pseudomonas aeruginosa (NiR-Pa) is a dimer consisting of two identical 60 kDa subunits, each of which contains one c and one d1 heme group. This enzyme, a soluble component of the electron-transfer chain that uses nitrate as a source of energy, can be induced by the addition of nitrate to the bacterial growth medium. NiR-Pa catalyzes the reduction of nitrite (NO2-) to nitric oxide (NO); in vitro, both cytochrome c551 and azurin are efficient electron donors in this reaction. NiR is a key denitrification enzyme, which controls the rate of the production of toxic nitric oxide (NO) and ultimately regulates the release of NO into the atmosphere. RESULTS: The structure of the orthorhombic form (P2(1)2(1)2) of oxidized NiR-Pa was solved at 2.15 A resolution, using molecular replacement with the coordinates of the NiR from Thiosphaera pantotropha (NiR-Tp) as the starting model. Although the d1-heme domains are almost identical in both enzyme structures, the c domain of NiR-Pa is more like the classical class I cytochrome-c fold because it has His51 and Met88 as heme ligands, instead of His17 and His69 present in NiR-Tp. In addition, the methionine-bearing loop, which was displaced by His17 of the NiR-Tp N-terminal segment, is back to normal in our structure. The N-terminal residues (5/6-30) of NiR-Pa and NiR-Tp have little sequence identity. In Nir-Pa, this N-terminal segment of one monomer crosses the dimer interface and wraps itself around the other monomer. Tyr10 of this segment is hydrogen bonded to an hydroxide ion--the sixth ligand of the d1-heme Fe, whereas the equivalent residue in NiR-Tp, Tyr25, is directly bound to the Fe. CONCLUSIONS: Two ligands of hemes c and d1 differ between the two known NiR structures, which accounts for the fact that they have quite different spectroscopic and kinetic features. The unexpected domain-crossing by the N-terminal segment of NiR-Pa is comparable to that of 'domain swapping' or 'arm exchange' previously observed in other systems and may explain the observed cooperativity between monomers of dimeric NiR-Pa. In spite of having similar sequence and fold, the different kinetic behaviour and the spectral features of NiR-Pa and NiR-Tp are tuned by the N-terminal stretch of residues. A further example of this may come from another NiR, from Pseudomonas stutzeri, which has an N terminus very different from that of the two above mentioned NiRs.


Asunto(s)
Proteínas Bacterianas , Nitrito Reductasas/química , Pseudomonas aeruginosa/enzimología , Secuencia de Aminoácidos , Sitios de Unión , Catálisis , Cristalización , Cristalografía por Rayos X , Grupo Citocromo c/química , Dimerización , Hemo/química , Hemoproteínas/química , Enlace de Hidrógeno , Modelos Moleculares , Datos de Secuencia Molecular , Nitrito Reductasas/metabolismo , Nitritos/metabolismo , Conformación Proteica , Estructura Secundaria de Proteína , Alineación de Secuencia , Agua/química , Agua/metabolismo
16.
Biochim Biophys Acta ; 914(2): 185-9, 1987 Aug 05.
Artículo en Inglés | MEDLINE | ID: mdl-3038191

RESUMEN

A circular dichroism study of carboxymethylated cytochrome c has been performed to obtain further information on the structural basis responsible for the observed changes in ligand binding and redox properties of the modified cytochrome c. The results give additional evidence of local structural changes occurring in the heme environment upon rupture of the (Met-80)-heme iron bond in the modified protein. This produces no alterations of the overall molecular conformation, but results in drastic changes in redox potential. In addition, analysis of the reversible conformational transitions induced by urea in the native and the modified proteins supports the idea that the modified derivative can be considered as an 'intermediate state' between the native and the fully unfolded protein.


Asunto(s)
Grupo Citocromo c , Hemoproteínas , Animales , Dicroismo Circular , Caballos , Metilación , Miocardio/metabolismo , Conformación Proteica , Desnaturalización Proteica , Urea
17.
Biochim Biophys Acta ; 788(2): 206-13, 1984 Jul 31.
Artículo en Inglés | MEDLINE | ID: mdl-6331514

RESUMEN

Binding of CO to single cuprous (half-apo) or cupric (met-apo) copper of hemocyanin is investigated by a new method which allows estimation of the total amount of CO bound to hemocyanin. Pure half-apo preparations could not be obtained with the molluscan hemocyanins from Helix pomatia and Octopus vulgaris, and a residual fraction of sites with coupled copper is always present. However, the determination of CO bound to the protein before and after addition of H2O2, used to oxidize selectively single copper sites, reveals that CO binds to half-apo Cu(I), and is released upon oxidation of copper to met-apo Cu(II). Binding of CO to half-apo is not associated to luminescence, proving that luminescence of native carboxyhemocyanin demands the presence of a second cuprous copper in the site. In addition, analysis of data indicates that the residual amount of coupled copper sites in partially copper-depleted hemocyanin is underestimated by the residual O2-copper band measured at 340 nm in air, while faithfully quantitated by the residual luminescence in the presence of CO. A distribution of the copper left in the site of three partially copper-depleted hemocyanins is depicted.


Asunto(s)
Monóxido de Carbono/metabolismo , Cobre/metabolismo , Hemocianinas , Animales , Sitios de Unión , Espectroscopía de Resonancia por Spin del Electrón , Caracoles Helix , Hemocianinas/metabolismo , Sustancias Macromoleculares , Octopodiformes , Análisis Espectral
18.
Biochim Biophys Acta ; 1034(3): 294-7, 1990 Jun 20.
Artículo en Inglés | MEDLINE | ID: mdl-2364086

RESUMEN

Direct electrochemistry of microperoxidase (the heme-undecapeptide from cytochrome c) has been followed at a bare and a gold plated RVC thin-layer electrode, using the spectropotentiostatic method or voltabsorptometry. Both techniques yield 'clean' and undistorted signals; their analysis easily provides quantitative information for the electrochemical parameters of microperoxidase and shows that spectroelectrochemistry is a powerful method to study the redox behavior of metalloproteins or their active site fragments.


Asunto(s)
Carbono , Oro , Peroxidasas , Electroquímica , Electrodos , Concentración de Iones de Hidrógeno , Oxidación-Reducción , Espectrofotometría
19.
Biochim Biophys Acta ; 534(1): 1-6, 1978 May 24.
Artículo en Inglés | MEDLINE | ID: mdl-26414

RESUMEN

Hemoglobin G. Ferrara is an abnormal human hemoglobin in which an asparagine residue is replaced by a lysyl residue at position beta57 (beta57 Asn replaced by Lys). Oxygen equilibria show that cooperativity and alkaline Bohr effect are maintained to normal levels while the acid Bohr effect appears increased; in addition, a smaller effect of diphosphoglycerate is also observed. Flash photolysis experiments performed as a function of protein concentration show that the fraction of quickly reacting form is always higher than that of human hemoglobin A. This fact, together with the increase of the oxygen affinity observed at acid pH values, may be related to an enhanced dissociation of the molecule into dimers. Several attempts to isolate the native chains by treatment of the protein with p-chloromercuribenzoate were unsuccessful due to the great instability of the isolated variant beta-chains, which precipitated completely during incubation with p-chloromercuribenzoate. Therefore, although the substitution is on the surface of the molecule, there are several properties of hemoglobin G. beta Ferrara which are clearly different from hemoglobin A.


Asunto(s)
Hemoglobinas Anormales , Ácidos Difosfoglicéricos/farmacología , Hemoglobinas Anormales/metabolismo , Humanos , Concentración de Iones de Hidrógeno , Sustancias Macromoleculares , Oxihemoglobinas/metabolismo , Fotólisis , Desnaturalización Proteica , Relación Estructura-Actividad
20.
Biochim Biophys Acta ; 742(3): 565-7, 1983 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-6301557

RESUMEN

Near ultraviolet and visible circular dichroism spectra of the carbomonoxy derivative of the hemoglobin component IV from trout Salmo irideus are pH-dependent in the range 6.2-7.8, and are affected by the presence of inositol hexaphosphate at pH 6.2. On the basis of previous studies, the spectral changes observed can be associated to the pH-dependent R4 leads to T4 transition occurring in the liganded protein. The CD spectra above 500 nm at low pH can be interpreted as due to release of the heme asymmetry in the T liganded conformation, in agreement with the movement of the iron toward the proximal histidine.


Asunto(s)
Carboxihemoglobina , Hemoglobinas , Regulación Alostérica , Animales , Dicroismo Circular , Concentración de Iones de Hidrógeno , Conformación Proteica , Protones , Trucha/sangre
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