RESUMO
1. The specific activities of erythrocyte membrane-bound acetylcholinesterase (EC 3.1.1.7.) and soluble hexokinase (EC 2.7.1.1.) in vitamin E deficient and vitamin E sufficient rabbits were investigated. 2. Acetylcholinesterase specific activities values of 43.4 in deficient and 57.4 in sufficient vitamin E rabbits were obtained. Hexokinase specific activity was not modified, and values of 3.31 in deficient and 3.6 in controls were found. 3. No peroxidation process was detected by us on vitamin E deficient diets. 4. These observations would suggest that the membrane stabilizing effect of vitamin E may be accomplished by a mode of action not necessarily related to its ability to prevent lipid peroxidation.
Assuntos
Acetilcolinesterase/metabolismo , Membrana Eritrocítica/enzimologia , Deficiência de Vitamina E/enzimologia , Animais , Hexoquinase/metabolismo , Masculino , Coelhos , Fatores de TempoRESUMO
1. In DMD patients the effect of chronic treatment with verapamil was investigated in the p-nitrophenylphosphatase from erythrocytes, the CK and LDH in serum and the functional activity of the muscle. 2. A different behaviour in the p-nitrophenylphosphatase from untreated compared to treated DMD patients and controls is supported by the following findings: (a) values of "n" altered in F- inhibition of the enzyme with Hill coefficients -1.43, -2.18 and -2.19; (b) Arrhenius plots between 16 and 40 degrees C with inflection points for the enzyme from treated DMD patients and controls and not from untreated DMD patients. 3. Although CK and LDH in serum and the muscular evaluation showed no statistical difference between both groups, evidence is presented that in treated DMD patients the interaction membrane-enzyme is different from untreated DMD patients.
Assuntos
4-Nitrofenilfosfatase/metabolismo , Músculos/fisiologia , Distrofias Musculares/enzimologia , Verapamil/administração & dosagem , Adolescente , Fosfatase Alcalina/antagonistas & inibidores , Fosfatase Alcalina/metabolismo , Criança , Pré-Escolar , Creatina Quinase/sangue , Eritrócitos/enzimologia , Humanos , L-Lactato Desidrogenase/sangue , Masculino , Distrofias Musculares/tratamento farmacológico , Fatores de Tempo , Verapamil/uso terapêuticoRESUMO
The extraction of white croaker skeletal myofibrils with KI rendered a residue in which a network of longitudinal and transverse filaments could be observed by scanning electron microscopy. A trypsin-like serine proteinase isolated from the same muscle was able to produce a complete and rapid disruption of the network, while major myofibrillar proteins were only slightly modified. This fact suggests that the disassembly of the cytoskeletal network may be an early event in the proteolysis of myofibrils. Desmin was not attacked by the proteinase under the assayed conditions, which indicates that some other unidentified component of the network would be the primary target of the action of the enzyme on myofibrils.
Assuntos
Citoesqueleto/ultraestrutura , Músculos/ultraestrutura , Miofibrilas/ultraestrutura , Serina Endopeptidases/metabolismo , Animais , Peixes , Microscopia Eletrônica de Varredura , Proteínas Musculares/isolamento & purificaçãoRESUMO
1. Fish skeletal muscle contains an alkaline thiol proteinase with a temperature optimum of 60 degrees C and undetectable activity below 50 degrees C. 2. The present study shows that fatty acids and sodium dodecyl sulphate (SDS) shifted the temperature-activity curve of the enzyme toward the lower temperature side. 3. All unsaturated fatty acids tested strongly stimulated proteolytic activity at 37 degrees C, whereas myristic acid was the only saturated fatty acid that produced an important degree of activation. 4. These effects could be observed at millimolar concentrations of the reagents.
Assuntos
Cisteína Endopeptidases/metabolismo , Perciformes/metabolismo , Animais , Ativação Enzimática/efeitos dos fármacos , Ácidos Graxos/farmacologia , Músculos/enzimologia , Dodecilsulfato de Sódio/farmacologiaRESUMO
1. The kinetic properties of the p-nitrophenylphosphatase (EC 3.1.3.1) from erythrocytes was investigated in DMD-patients and DMD-carriers. 2. A different allosteric behaviour in the p-nitrophenylphosphatase from DMD-patients and DMD-carriers compared to controls is supported by the following findings: (a) values of n altered in F- inhibition of (K+)-activated p-nitrophenylphosphatase with Hill coefficients -1.5, -2.2 and -3.1; (b) heterotropic effect of increased concentration of Mg2+ on F- inhibition which is reverted by K+ in DMD-carriers and in control, but not in DMD-patients. 3. Evidence is presented showing that in DMD-patients and in DMD-carriers the interaction membrane-enzyme is different from the corresponding controls.
Assuntos
4-Nitrofenilfosfatase/sangue , Fosfatase Alcalina/sangue , Membrana Eritrocítica/enzimologia , Distrofias Musculares/enzimologia , Monoéster Fosfórico Hidrolases/sangue , 4-Nitrofenilfosfatase/antagonistas & inibidores , Regulação Alostérica , Membrana Eritrocítica/fisiologia , Feminino , Fluoretos/farmacologia , Heterozigoto , Humanos , Técnicas In Vitro , Cinética , Magnésio/fisiologia , Masculino , Distrofias Musculares/sangueRESUMO
The allosteric behaviour of 4-nitrophenylphosphatase from membrane erythrocytes was investigated in Duchenne muscular dystrophy (DMD) patients, in female carriers and in healthy controls. Cooperative type kinetics with a Hill coefficient of -2.19, -1.71 and -1.54 has been obtained from the inhibition by fluoride in controls, female carriers and Duchenne patients, respectively. Our observation supports the previously described membrane abnormalities in DMD erythrocytes and may extend then to female carriers.