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1.
Leukemia ; 34(1): 257-270, 2020 01.
Artículo en Inglés | MEDLINE | ID: mdl-31148590

RESUMEN

Multiple myeloma is the second most frequent hematological cancer after lymphoma and remains an incurable disease. The pervasive support provided by the bone marrow microenvironment to myeloma cells is crucial for their survival. Here, an unbiased assessment of receptor tyrosine kinases overexpressed in myeloma identified ROR2, a receptor for the WNT noncanonical pathway, as highly expressed in myeloma cells. Its ligand, WNT5A is the most abundant growth factor in the bone marrow of myeloma patients. ROR2 mediates myeloma cells interactions with the surrounding bone marrow and its depletion resulted in detachment of myeloma cells from their niche in an in vivo model, triggering apoptosis and thus markedly delaying disease progression. Using in vitro and ex vivo 3D-culture systems, ROR2 was shown to exert a pivotal role in the adhesion of cancer cells to the microenvironment. Genomic studies revealed that the pathways mostly deregulated by ROR2 overexpression were PI3K/AKT and mTOR. Treatment of cells with specific PI3K inhibitors already used in the clinic reduced myeloma cell adhesion to the bone marrow. Together, our findings support the view that ROR2 and its downstream targets represent a novel therapeutic strategy for the large subgroup of MM patients whose cancer cells show ROR2 overexpression.


Asunto(s)
Médula Ósea/metabolismo , Mieloma Múltiple/patología , Receptores Huérfanos Similares al Receptor Tirosina Quinasa/metabolismo , Microambiente Tumoral/fisiología , Animales , Médula Ósea/patología , Adhesión Celular/fisiología , Xenoinjertos , Humanos , Ratones , Mieloma Múltiple/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Transducción de Señal/fisiología
2.
Food Funct ; 9(5): 2913-2921, 2018 May 23.
Artículo en Inglés | MEDLINE | ID: mdl-29726862

RESUMEN

Avenanthramides (AVNs) are natural polyphenols obtained from oat sprouts and can also be chemically synthetized. The aim of the present study was to assess the anticancer, anti-inflammatory and antioxidant effects of individual synthetized AVNs (s-2c, s-2p, s-2f) and a natural AVN mixture (n-MIX) on CaCo-2 and Hep3B cancer cells. In CaCo-2, the AVN s-2c was found to be the most cytotoxic followed by the n-MIX. In Hep3B cells, a marked cytotoxic effect was found but no significant difference was observed between the synthesized AVNs and the n-MIX. In both CaCo-2 and Hep3B cells, natural and synthetic AVNs activated caspases 8 and 3, and the n-MIX and the AVN s-2c were also able to activate caspase 2. Both synthetic and natural AVNs downregulated pro-survival genes hTERT, COX-2 and MDR1, inhibited the activity of pro-inflammatory COX-2 enzyme and reduced prostaglandin E2 levels, showing the potent chemopreventive effects of these oat-derived phytochemicals. Synthetic AVN s-2c was found to have the highest chemical antioxidant capacity, as indicated by ORAC, DPPH and ABTS values, whereas all AVNs and n-MIX were shown to have similar intracellular antioxidant activity, evaluated by means of the DCFH-DA assay. As AVNs have high bioavailability in humans, results of this study suggest that oat-based foods, fortified with AVNs, could be an alternative to produce functional foods with anticancer, anti-inflammatory and antioxidant effects for health benefits.


Asunto(s)
Caspasa 2/metabolismo , Caspasa 3/metabolismo , Caspasa 8/metabolismo , Ciclooxigenasa 2/metabolismo , Cisteína Endopeptidasas/metabolismo , Extractos Vegetales/farmacología , Telomerasa/metabolismo , ortoaminobenzoatos/farmacología , Subfamilia B de Transportador de Casetes de Unión a ATP/genética , Subfamilia B de Transportador de Casetes de Unión a ATP/metabolismo , Antioxidantes/síntesis química , Antioxidantes/farmacología , Avena/química , Células CACO-2 , Caspasa 2/genética , Caspasa 3/genética , Caspasa 8/genética , Ciclooxigenasa 2/genética , Cisteína Endopeptidasas/genética , Dinoprostona/metabolismo , Humanos , Extractos Vegetales/síntesis química , Telomerasa/genética , ortoaminobenzoatos/síntesis química
3.
Food Chem ; 218: 356-364, 2017 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-27719921

RESUMEN

Vitexin-2-O-xyloside (XVX) from Beta vulgaris var. cicla L. (BVc) seeds, betaxanthin (R1) and betacyanin (R2) fractions from Beta vulgaris var. rubra L. (BVr) roots were combined and tested for cytotoxicity in CaCo-2 colon cancer cells. XVX was the most cytotoxic molecule, but the combination of XVX with R1 and R2 significantly prolonged its cytotoxicity. Cytotoxicity was mediated by the intrinsic apoptotic pathway, as shown by an increase in Bcl2-like protein 4, cleaved Poly ADP-Ribosyl Polymerase 1 and cleaved Caspase 3 levels with a parallel decrease in anti-apoptotic protein B-cell leukemia/lymphoma 2 levels. R1 and R2, used alone or in combination, reduced oxidative stress triggered by H2O2 in CaCo-2 cells. Betalains dampened cyclooxygenase-2 and interleukin-8 mRNA expression after lipopolysaccharide induction in CaCo-2, showing an anti-inflammatory action. Our results support the use of a cocktail of R1, R2 and XVX as a chemopreventive tool against colon cancer.


Asunto(s)
Beta vulgaris/química , Betalaínas/farmacología , Flavonoides/farmacología , Glicósidos/farmacología , Antiinflamatorios/farmacología , Apoptosis/efectos de los fármacos , Linfocitos B/metabolismo , Células CACO-2 , Caspasa 3/genética , Caspasa 3/metabolismo , Quimioprevención , Neoplasias del Colon/tratamiento farmacológico , Ciclooxigenasa 2/genética , Ciclooxigenasa 2/metabolismo , Humanos , Peróxido de Hidrógeno , Interleucina-8/genética , Interleucina-8/metabolismo , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Estrés Oxidativo/efectos de los fármacos , Extractos Vegetales/farmacología , Raíces de Plantas/química , ARN Mensajero/genética , ARN Mensajero/metabolismo , Especies Reactivas de Oxígeno/metabolismo
4.
Food Funct ; 7(12): 4772-4780, 2016 Dec 07.
Artículo en Inglés | MEDLINE | ID: mdl-27812566

RESUMEN

Betacyanins (BC) were purified from beetroot (Beta vulgaris var. rubra L.) and tested, alone or in combination with vitexin-2-O-xyloside (XVX) from Beta vulgaris var. cicla L., for their ability to reduce the proliferation rate in T24 bladder cancer cells. Combination of BC and XVX exhibited a synergistic effect concerning the inhibition of proliferation in T24 cancer cells at 24 and 48 h but not after 72 h of incubation. The induction of apoptosis was evidenced by means of fluorescence activated cell sorting (FACS) analysis, as well as through the increase in caspase 3 and 8 activities. Using RTqPCR experiments, it was shown that the combination of XVX + BC was able to enhance the expression levels of pro-apoptotic BAX and downregulate anti-apoptotic BIRC5 (survivin), as well as pro-survival CTNNB1 (ß-catenin). The most evident effect of BC was the increase of the activity of caspase 8, leading to induction of extrinsic apoptosis. Moreover, XVX, BC and their combination showed no cytotoxic effect on normal human skin NCTC 2544 keratinocytes. These results demonstrated the efficacy and the mechanisms of the action of BC and XVX, extracted from edible plants, and suggested that a diet or a nutrition supplement, enriched with these bioactive molecules, could be used in the prevention of human bladder cancer.


Asunto(s)
Anticarcinógenos/farmacología , Betacianinas/farmacología , Proliferación Celular/efectos de los fármacos , Flavonoides/farmacología , Glicósidos/farmacología , Anticarcinógenos/administración & dosificación , Apoptosis , Beta vulgaris/química , Betacianinas/administración & dosificación , Betacianinas/química , Línea Celular Tumoral , Regulación hacia Abajo , Flavonoides/administración & dosificación , Glicósidos/administración & dosificación , Humanos , Estructura Molecular
5.
Eur Rev Med Pharmacol Sci ; 17(16): 2129-35, 2013 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-23893177

RESUMEN

BACKGROUND: Pain is the most common reason people see doctors in developed Countries and a very common cause of access in Emergency Department (ED). The combination acetaminophen/codeine represents the standard medication in the second step of the WHO analgesic scale and codeine is one of the most commonly used opioid analgesic for a variety of pain conditions. However, many aspects related to safety and efficacy are still undefined. AIM: To summarize and review the results of the most relevant studies on the efficacy and safety profile of acetaminophen/codeine combination in the treatment of pain of different origin. MATERIALS AND METHODS: We performed a literature search to identify and evaluate all relevant english-language randomized controlled trials (RCTs), meta-analyses and reviews about the codeine plus paracetamol combination in the treatment of pain from any source. RESULTS: Acetaminophen/codeine combination is effective in the treatment of moderate to severe pain in all setting analyzed in this study, which include headache, postoperative, osteoarticular and post-traumatic. The best results in terms of safety and efficacy have been obtained in postoperative pain. Efficacy of acetaminophen/codeine combination is not inferior to NSAIDs. CONCLUSIONS: Acetaminophen/codeine combination is effective in the treatment of pain, through a synergistic action of the two molecules, and is not inferior to NSAIDs. Side effects of acetaminophen/codeine are usually minor, differently from NSAIDs, which may induce some potentially life threatening conditions.


Asunto(s)
Acetaminofén/uso terapéutico , Analgésicos no Narcóticos/uso terapéutico , Analgésicos Opioides/uso terapéutico , Codeína/uso terapéutico , Acetaminofén/administración & dosificación , Acetaminofén/efectos adversos , Analgésicos no Narcóticos/administración & dosificación , Analgésicos no Narcóticos/efectos adversos , Analgésicos Opioides/administración & dosificación , Analgésicos Opioides/efectos adversos , Antiinflamatorios no Esteroideos/uso terapéutico , Codeína/administración & dosificación , Codeína/efectos adversos , Combinación de Medicamentos , Sinergismo Farmacológico , Humanos , Dolor/tratamiento farmacológico , Dolor/etiología , Ensayos Clínicos Controlados Aleatorios como Asunto , Índice de Severidad de la Enfermedad
6.
Rev. bras. reumatol ; 39(4): 211-6, jul.-ago. 1999. tab
Artículo en Portugués | LILACS | ID: lil-270373

RESUMEN

HTLV-I/II são oncorretrovírus associados à leucemia de células T do adulto e à mielopatia crônica progressiva. Poliartrite crônica simétrica e complexo sicca são eventualmente encontrados em casos de infecções por HTLV-I/II. Um recente estudo japonês evidenciou prevalência de 20 por cento de anticorpos anti-HTLV-I em pacientes com artrite reumatóide (AR), um achado significante comparativamente a controles de banco de sangue. Tanto quanto os autores sabem, não há estudos brasileiros a esse respeito. Objetivo: Avaliar a prevalência de anticorpos anti-HTLV-I/II em pacientes com AR, usando um ensaio enzimático (ELISA) e, quando necessário, Western blot para confirmação de positividade. Métodos: Foram estudados 69 pacientes com AR (55 mulheres e 14 homens, todos caucasóides), diagnosticados de acordo com os critérios do Colégio Americano de Reumatologia. A média de idade dos pacientes foi de 51 anos, e a duração média da doença, de 8 anos. Os soros desses pacientes foram inicialmente testados para anticorpos anti-HTLV-I/II em ELISA de segunda geração (Ortho). A positividade foi confirmada através de Western blot (Gene Labs, kit 2.4). Os grupos-controles consistiram de 1.416 doadores de banco de sangue testados por ELISA e 33 pacientes consecutivos com lúpus eritematoso sistêmico (LES), também testados em ELISA. O teste de Fisher foi utilizado para análise estatística, sendo valores de p<0,05 considerados relevantes. Resultados: Anticorpos anti-HTLV-I/II foram detectados em 5 dos 69 pacientes com AR através de ELISA (7 por cento). Destes, 4 (5,7 por cento) tiveram resultados confirmatórios para anti-HTLV-I em Western blot. Os 4 pacientes eram soropositivos para fator reumatóide, mas nenhum apresentava doença ativa. Nos doadores de sangue, 18 soros (1,27 por cento) foram positivos para anti-HTLV-I/II em ELISA (p=0,004, significativo em relação ao grupo com AR testado em ELISA). Nos pacientes com LES, nenhum caso de positividade foi encontrado em ELISA (p=0,07, insignificante em relação aos pacientes com AR). Conclusão: No estudo, a prevalência de anticorpos contra HTLV-I/II em pacientes com AR foi estatisticamente relevante quando comparada com a de doadores de sangue, mas não-significativa quando comparada com a de pacientes com LES. O papel da infecção por HTLV-I/II na AR deve ser clareado em estudos adicionais


Asunto(s)
Anticuerpos , Artritis Reumatoide , Anticuerpos Antideltaretrovirus , Retroviridae
7.
J Am Geriatr Soc ; 47(6): 664-71, 1999 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-10366164

RESUMEN

BACKGROUND: The prevalence of heart failure (HF) increases with age, and HF is a major cause of disability and mortality in older persons. Detection of HF in epidemiological studies has relied on criteria validated only in young and middle-age adults, and, therefore, may prove inadequate in older subjects, because they do not take into account the pathophysiologic and clinical peculiarities of HF in old age. Thus, the true prevalence of HF in the older general population remains uncertain and has probably been underestimated in previous studies. Moreover, the mechanism and the extent by which HF hinders physical functioning in older people has not been fully elucidated. OBJECTIVES: This paper describes the design of the ICARe study, carried out in an older home-dwelling population to collect data about: (1) the sensitivity and specificity of diagnostic criteria used previously in epidemiological studies of HF; (2) the prevalence of the different pathophysiologic forms of HF; and (3) the impact of HF on overall health status, and on physical functioning, in the absence or presence of chronic comorbidity. DESIGN AND SETTING: This was a cross-sectional survey. Eligible were all community-dwelling persons aged 65 years or older recorded in the Registry Office of Dicomano, a small town nearby Florence (Italy). All the domains of multidimensional geriatric assessment were explored through different phases of the study (home interview, laboratory testing, geriatric visit) that comprised an extensive cardiopulmonary instrumental assessment including: color Doppler echocardiography, echotomography of the carotid arteries used in an original method to determine arterial compliance, and bell spirometry. Presence of major chronic conditions was ascertained by predefined, standard algorithms that were based largely on clinical examination. RESULTS: There were 864 older persons eligible for the ICARe study. Even with a substantial decline from home interview (91.2%) to the cardiopulmonary study (71.1%), the adherence rate remained high throughout the study, and the population examined was fairly representative of the original eligible population. Thus, we believe that the data collected in this study offer a unique opportunity to assess the validity of the diagnostic clinical criteria for HF in the general older population, to identify the pathophysiology underlying the syndrome, and to investigate the relationship between HF, comorbidity, and disability.


Asunto(s)
Insuficiencia Cardíaca/epidemiología , Actividades Cotidianas , Distribución por Edad , Anciano , Anciano de 80 o más Años , Cognición , Comorbilidad , Estudios Transversales , Femenino , Insuficiencia Cardíaca/diagnóstico , Insuficiencia Cardíaca/fisiopatología , Insuficiencia Cardíaca/psicología , Humanos , Entrevistas como Asunto/métodos , Italia/epidemiología , Masculino , Prevalencia , Sensibilidad y Especificidad , Encuestas y Cuestionarios
8.
Pediatr Med Chir ; 17(2): 139-42, 1995.
Artículo en Italiano | MEDLINE | ID: mdl-7610077

RESUMEN

Adolescent had in the past rarely been affected by sexually transmitted infections. Nowadays they must be considered possibly running such risks as they begin their sexual activity earlier or do not know enough about these kinds of troubles. Therefore a valid primary prevention is necessary based upon correct information.


Asunto(s)
Enfermedades de Transmisión Sexual/epidemiología , Adolescente , Conducta del Adolescente , Condones , Femenino , Humanos , Masculino , Padres , Educación del Paciente como Asunto , Educación Sexual , Conducta Sexual , Enfermedades de Transmisión Sexual/prevención & control
9.
J Gerontol ; 46(2): M52-6, 1991 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-1997573

RESUMEN

A survey of the health and social conditions of a representative sample of 967 persons aged 60 years and older from the city of Florence, Italy, was undertaken in 1980. In 1987, a follow-up survey of this cohort was performed. There were 391 documented deaths, 408 survivors, and 168 individuals who could not be located. Functional ability at baseline was assessed using a World Health Organization 14-item scale. Indicators of physical health status included chronic disease status, number of drugs, physician visits, and days of hospitalization. After adjustment for age and sex, both functional ability and indicators of physical health status were found to be independent, statistically significant predictors of mortality. The results of this study further support the view that biomedical and functional assessment are both necessary for a comprehensive evaluation of the older population.


Asunto(s)
Actividades Cotidianas , Estado de Salud , Medio Social , Anciano , Anciano de 80 o más Años , Enfermedad Crónica , Estudios de Cohortes , Femenino , Estudios de Seguimiento , Servicios de Salud/estadística & datos numéricos , Humanos , Italia/epidemiología , Masculino , Persona de Mediana Edad , Mortalidad , Probabilidad , Estudios Prospectivos , Autocuidado , Factores Sexuales
11.
Med Microbiol Immunol ; 176(3): 123-30, 1987.
Artículo en Inglés | MEDLINE | ID: mdl-3600497

RESUMEN

The antibacterial activity of metal complexes of ovotransferrin was tested "in vitro" against different bacterial species and the Zn2+ saturated ovotransferrin appeared to be the most active by comparison with the apo-protein and other metal complexes. Appropriate controls showed that such an effect was neither due to Zn2+ ions, nor to iron deprivation, but to a specific activity of the Zn-ovotransferrin complex. This antibacterial activity required a direct contact of Zn-ovotransferrin with the bacterial surface. In vivo experiments confirmed the higher antibacterial activity of Zn-ovotransferrin as compared with the apo-form.


Asunto(s)
Bacterias/efectos de los fármacos , Conalbúmina/farmacología , Proteínas del Huevo/farmacología , Metales/farmacología , Zinc/farmacología , Animales , Estabilidad de Medicamentos , Cobayas
12.
Biotechnol Bioeng ; 27(5): 704-10, 1985 May.
Artículo en Inglés | MEDLINE | ID: mdl-18553726

RESUMEN

Glucagon was immobilized onto Sepharose matrices activated with CNBr or tresyl chloride, as a function of several parameters including pH of coupling, concentration of added polypeptide, and presence or absence of urea. The hormone was linked to the matrix through a single point per molecule, namely, the epsilon -amino group of Lys(12) when the coupling was carried out at alkaline pH, or the imidazole group of His(1) when the coupling was carried out at acidic pH. Glucagon immobilized at alkaline pH interacted specifically with soluble glucogon. The extent of self-association was similar to that of free glucagon, which exists in solution in a monomer-trimer equilibrium whose association constant is highly dependent on the characteristics of the buffer (pH, ionic strength, and nature of anions). The immobilized hormone proved to be suitable for the purification of the free one from a pancreatic extract. After a preliminary treatment with charcoal-dextran, the extract was percolated on a glucagon-Sepharose column under associating conditions (high concentrations of salting out anions and alkaline pH) and then, following a washing to remove extraneous compounds, the specifically bound hormone was eluted under dissociating conditions (low ionic strength). The subunit exchange chromatography of the extract gave a ca. 90% pure product. The overall recovery of the process was ca. 66%. The leakage of immobilized hormone was 40% in the case of CNBr activation of Sepharose and 15% in the case of tresyl chloride activation, after an eight-day treatment under working conditions.

13.
J Inorg Biochem ; 23(2): 109-17, 1985 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-3973582

RESUMEN

Dithionite causes the depletion of dioxygen from suspensions of erythrocytes by reduction of the external dioxygen and not by diffusion into the cell. The molar enthalpy for the reduction shows a small difference with respect to the values found for free hemoglobin; and the normal stoichiometry of 2 moles dithionite/mole dioxygen found there is not observed with erythrocytes. At low hematocrit, the stoichiometry is 2.6:1 and decreases to 1.5:1 at high hematocrit. The change is not due to differences in the hemoglobin saturation or to an inability of dithionite to reduce all dioxygen present at the higher hematocrit. Neither catalase nor peroxidase added to the extracellular volume significantly alters the stoichiometry or the enthalpy of dioxygen reduction by dithionite. Addition of superoxide dismutase, however, restores the normal stoichiometry at high hematocrit and further increases the stoichiometry at low hematocrit. The calorimetrical signal of hydrogen peroxide, clearly seen with free dioxygen, is not present with erythrocytes. In all these cases the total heat evolved is the same.


Asunto(s)
Ditionita/farmacología , Eritrocitos/efectos de los fármacos , Oxihemoglobinas/metabolismo , Sulfitos/farmacología , Animales , Calorimetría , Bovinos , Eritrocitos/metabolismo , Técnicas In Vitro , Superóxido Dismutasa/farmacología
14.
Biochim Biophys Acta ; 789(1): 20-5, 1984 Aug 28.
Artículo en Inglés | MEDLINE | ID: mdl-6466687

RESUMEN

The effect of pH and D-glycerate 2,3-bisphosphate on the oxidation-reduction equilibria of human hemoglobin, normal and modified at the SH(beta 93) groups by reaction with cystine dimethylester has been studied with the aim of comparing the redox equilibria with the oxygen equilibria previously studied under the same experimental conditions. Analysis of data has shown that: (i) the same groups are involved in the oxygenation and oxidation alkaline Bohr effect; (ii) the pK values of these groups are lower in met-hemoglobin than in oxyhemoglobin; (iii) the difference in the affinity for D-glycerate 2,3-bisphosphate of ferric and deoxyhemoglobin is pH-independent in the normal protein, while significantly decreasing with a decrease in pH in the modified protein; (iv) the high cooperativity of the redox process (also occurring at acid pH) and the reduced oxidation Bohr effect observed in the modified protein are consistent with the destabilization of the T structure induced by the bulky reagent bound to the SH(beta 93) groups of the protein.


Asunto(s)
Cisteína , Ácidos Difosfoglicéricos/farmacología , Hemoglobinas/metabolismo , 2,3-Difosfoglicerato , Humanos , Concentración de Iones de Hidrógeno , Matemática , Metahemoglobina/metabolismo , Oxidación-Reducción , Oxihemoglobinas/metabolismo
15.
J Biol Chem ; 259(11): 6730-8, 1984 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-6725269

RESUMEN

The kinetics of the reaction with oxygen and carbon monoxide of the homodimeric hemoglobin from the bivalve mollusc Scapharca inaequivalvis has been extensively investigated by flash and dye-laser photolysis, temperature jump relaxation, and stopped flow methods. The results indicate that cooperativity in ligand binding, already observed for oxygen at equilibrium, finds its kinetic counterpart in a large decrease of the oxygen dissociation velocity in the second step of the binding reaction. In the case of carbon monoxide, cooperativity is clearly evident in the increase of the combination velocity constant as the reaction proceeds. Therefore, the ligand-binding kinetics of this dimeric hemoglobin shows the characteristic features of the corresponding reactions of tetrameric hemoglobins. Analysis of the data in terms of the allosteric model proposed by Monod et al. (Monod, J., Wyman, J., and Changeux, J. P. (1965) J. Mol. Biol. 12, 88-118) has shown that the values of the allosteric parameters cannot be fixed uniquely for a dimeric hemoglobin. The rapid changes in absorbance observed at the isosbestic points of unliganded and liganded hemoglobin following laser photolysis provided a value of 7 X 10(4) S-1 at 20 degrees C for the rate of the ligand-free quarternary conformational change, postulated on the basis of cooperative ligand binding. Comparison of the rapid absorbance changes observed during ligand rebinding in this hemoglobin with those observed in tuna hemoglobin indicate that, at full photolysis, binding to the T state is followed by further binding and conversion to the liganded R state; at partial photolysis, population of the liganded T state occurs immediately and is followed by a decay to the liganded R state upon further ligand binding. These new results, in conjunction with previous equilibrium data on the same system, show unequivocally that the presence of two different types of chain is not an absolute prerequisite for cooperativity in hemoglobins, contrary to currently accepted ideas.


Asunto(s)
Hemoglobinas/metabolismo , Moluscos/metabolismo , Animales , Monóxido de Carbono/metabolismo , Cinética , Rayos Láser , Sustancias Macromoleculares , Oxígeno/metabolismo , Fotólisis , Temperatura
16.
Biochim Biophys Acta ; 785(1-2): 75-80, 1984 Feb 28.
Artículo en Inglés | MEDLINE | ID: mdl-6559602

RESUMEN

Pre-steady-state and steady-state kinetics of the porcine pancreatic beta-kallikrein-B (EC 3.4.21.35) catalyzed hydrolysis of ZArgONp have been determined between pH 2.4 and 8. The results are consistent with a minimum three-step mechanism involving an acyl-enzyme intermediate: (see formula). The formation of the E X S complex may be regarded as a pseudoequilibrium process; the minimum values for k+1 are 5.9 X 10(6) M-1 X s-1 (pH 5.5) and 9.4 X 10(5) M-1 X s-1 (pH 2.4) and that for k-1 is 600 s-1. The value of k-1/k+1 (= Ks) changes from 102 microM at pH greater than or equal to 5.5 to 638 microM at pH less than 2.4. The pH dependence of k+2 conforms to two ionizing groups, in the E X S complex, with pKa values of 3.4 +/- 0.1 and 7.05 +/- 0.10. The pH profile of k+2/Ks (= kcat/Km) reflects the ionization of two groups, in the free enzyme, with pKa values of 4.2 +/- 0.1 and 7.05 +/- 0.10. The pH dependence of k+3 implicates two ionizing groups in the deacylation step with pKa values of 4.6 +/- 0.1 and 7.0 +/- 0.1. At acid pH values (pH 2.4-4.4), k+3 is rate-limiting in catalysis, whereas for pH values higher than 4.4, k+2 becomes rate-limiting. The observed neutral and acid ionizations probably reflect the acid-base equilibrium of His-57 and Asp-189 involved in the central site of beta-kallikrein-B. The structural basis for the specificity and catalytic behaviour of this proteinase are discussed and a role for Ser-226 is pinpointed.


Asunto(s)
Arginina/análogos & derivados , Concentración de Iones de Hidrógeno , Calicreínas/metabolismo , Páncreas/enzimología , Animales , Arginina/metabolismo , Hidrólisis , Cinética , Sustancias Macromoleculares , Matemática , Porcinos
17.
Mol Cell Biochem ; 60(2): 163-81, 1984.
Artículo en Inglés | MEDLINE | ID: mdl-6708945

RESUMEN

Steady-state and pre-steady-state kinetic data for the trypsinogen catalyzed hydrolysis of a series of synthetic substrates (i.e. p-nitrophenyl esters of N-alpha-carbobenzoxy-L-amino acids) have been obtained as a function of pH (3.4-8). Moreover, the effect of ethylamine on the hydrolysis of a neutral substrate and benzamidine binding have been extensively studied. In order to obtain direct information on the transition of trypsinogen to a beta-trypsin-like structure, the role of the effector dipeptide Ile-Val on the catalytic and ligand binding properties of the zymogen has been investigated. Kinetic and thermodynamic data for beta-trypsin and alpha-chymotrypsin are also reported for the purpose of an homogeneous comparison of the various (pro)enzymes. Under all the experimental conditions, kinetic data for (pro)enzyme catalysis are consistent with the minimum three-step mechanism: (formula; see text) involving the acyl intermediate E X P. In the presence of Ile-Val dipeptide, trypsinogen assumes catalytic and ligand binding properties that are reminiscent of activated beta-trypsin. This is at variance with free trypsinogen, which shows a alpha-chymotrypsin-like behavior. The large differences in the results of kinetic and thermodynamic measurements for free trypsinogen, as compared to its binary adduct with Ile-Val, can be ascribed to the substantial differences in the two molecular species, which include the spatial orientation of Asp189.


Asunto(s)
Dipéptidos/farmacología , Tripsinógeno/metabolismo , Animales , Benzamidinas/metabolismo , Bovinos , Activación Enzimática/efectos de los fármacos , Etilaminas/farmacología , Concentración de Iones de Hidrógeno , Técnicas In Vitro , Cinética , Conformación Proteica/efectos de los fármacos , Especificidad por Sustrato , Termodinámica
18.
Biochem Pharmacol ; 33(1): 109-13, 1984 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-6322790

RESUMEN

The interaction between bepridil and mitochondrial cytochrome c oxidase has been studied using the purified enzyme either in aqueous suspensions in the presence of detergents, or embedded into phospholipid vesicles. The investigation, systematically extended to nonactin and valinomycin for comparison, showed that: (a) valinomycin and nonactin induce similar changes in the visible absorption spectrum of cytochrome oxidase; these changes are quite different from those induced by bepridil. (b) The three compounds have an effect on the functional properties of purified, solubilized oxidase which may be related to binding. In particular, bepridil displays a complex pH-dependent effect which at concentrations below 50 microM results in a stimulation of the activity of approximately 30% starting with the oxidized resting enzyme. At variance with valinomycin and nonactin, the stimulatory effect is the same, within the errors, for the detergent-suspended, the vesicle-embedded and even the Keilin-Hartree particles. (c) In the case of detergent-suspended oxidase, the stimulatory effect of bepridil is also similar whether the enzyme is in the resting or in the pulsed state. If the oxidase is embedded into vesicles, however, the pulsed state is significantly more sensitive to bepridil than the resting one. These results are discussed in the light of the possible role assigned to pulsed oxidase in the regulation of the electron flux through the respiratory chain.


Asunto(s)
Complejo IV de Transporte de Electrones/metabolismo , Liposomas/metabolismo , Pirrolidinas/farmacología , Animales , Antibacterianos/farmacología , Bepridil , Bovinos , Macrólidos , Mitocondrias Cardíacas/enzimología , Soluciones , Espectrofotometría , Valinomicina/farmacología
20.
J Mol Biol ; 170(4): 1009-18, 1983 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-6644811

RESUMEN

Oxygen equilibrium curves of the dimeric and tetrameric hemoglobin components of Scapharca inaequivalvis were determined at several temperatures. The oxygen equilibrium curves were analyzed by the two-step and four-step oxygen equilibrium schemes of Adair for the dimeric and tetrameric hemoglobins, respectively. The enthalpy and entropy changes for each oxygenation step were determined by the temperature dependences of the Adair constants using van't Hoff equations. Neither dimeric nor tetrameric hemoglobins release protons or anions upon oxygenation under the experimental conditions of the present study. The enthalpy and entropy changes are non-uniform with respect to the oxygenation step and do not need to be corrected for the oxygenation-linked release of protons and anions. For the tetrameric hemoglobin, enthalpy-entropy compensation was observed between the first, second and third steps of oxygenation. The present results suggest that the origin of the co-operative oxygenation is primarily entropic for both hemoglobin components of S. inaequivalvis. Comparison of these data with those obtained on other hemoglobins shows that no simple generalization can be made as to the thermodynamic nature of co-operativity in oxygen binding.


Asunto(s)
Hemoglobinas/metabolismo , Oxígeno/metabolismo , Animales , Sustancias Macromoleculares , Moluscos , Temperatura , Termodinámica
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