RESUMO
Plasma NO-binding activity was studied in patients with various forms of hematological malignancies. The method used in the study quantitatively evaluated the plasma capacity to bind NO, which reflects the intensity of NO production and the degree of patient's stress resistance. Plasma NO-binding activity significantly decreases in patients with hematological malignancies. Glucocorticoid treatment promotes the decrease in plasma NO-binding activity, which was dose-dependent.
Assuntos
Glucocorticoides/farmacologia , Neoplasias Hematológicas/sangue , Óxido Nítrico/sangue , Adolescente , Adulto , Idoso , Feminino , Glucocorticoides/uso terapêutico , Neoplasias Hematológicas/tratamento farmacológico , Humanos , Masculino , Pessoa de Meia-Idade , Ligação ProteicaRESUMO
ATP quenches light-dependent phosphodiesterase (PDE) activation in rod outer segments presumably due to rhodopsin phosphorylation. Here we compared the efficiency of phosphorylated and non-phosphorylated rhodopsins as PDE activators in a reconstituted cell-free system. It is shown that the ability of phosphorylated membranes to activate this enzyme is suppressed compared with non-phosphorylated ones.
Assuntos
Luz , Fosfoproteínas/farmacologia , Diester Fosfórico Hidrolases/metabolismo , Células Fotorreceptoras/enzimologia , Pigmentos da Retina/metabolismo , Pigmentos da Retina/farmacologia , Rodopsina/metabolismo , Rodopsina/farmacologia , Segmento Externo da Célula Bastonete/enzimologia , Animais , Bovinos , Sistema Livre de Células , Ativação Enzimática/efeitos dos fármacos , Ativação Enzimática/efeitos da radiação , Fosforilação , Relação Estrutura-AtividadeRESUMO
Some properties of homogeneous transketolase (sedoheptulose-7-phosphate: D-glyceraldehyde-3-phosphate glycolaldehydetransferase, EC 2.2.1.1) from pig liver were studied. It was shown that the pH optimum of the transketolase reaction lies within the range of 7.8-8.2; the isoelectric point is at pH 7.6-7.8. The molecular weight of transketolase is 138 000 +/- 3000 as determined by the sedimentation equilibrium method. The enzyme molecular is a tetramer of the alpha 2 beta 2 type. The molecular weights of the alpha- and beta-subunits determined by polyacrylamide gel in the presence of sodium dodecyl sulphate are 52 000-56 000 and 27 000-29 000, respectively. Transketolase contains about 2 mol of thiamine pyrophosphate per mol of protein and does not require metal ions for its catalytic activity.
Assuntos
Fígado/enzimologia , Transcetolase/metabolismo , Animais , Fenômenos Químicos , Química , Metais/análise , Peso Molecular , Suínos , Tiamina Pirofosfato/metabolismoRESUMO
Transketolase from pig liver contains a tightly bound coenzyme, which is not split off after severe treatment (e.g. boiling for 12 hrs in 1 n. HCl, 30 min boiling in 2 n HCl, boiling in 1% DS-Na, standing in 6 M solution of quanidine chloride, etc.). The proteolysis of the enzyme results in a coenzyme-containing material differing in some of its properties from free thiamine by pyrophosphate. The data obtained suggest that pig liver transketolase contains covalently bound thiamine pyrophosphate.
Assuntos
Fígado/enzimologia , Tiamina Pirofosfato , Transcetolase/metabolismo , Animais , Ligação Proteica , SuínosRESUMO
Some properties of homogeneous transketolase from pig liver were studied. It was shown that the pH optimum of the transketolase reaction lies within the range of 7.8--8.2. The isoelectric point is at pH 7.6--7.8. The molecular weight of transketolase is 138,000 +/- 3,000 as determined by the sedimentation equilibrium method and about 152,000 according to the data from gel filtration through Sephadex G-200. The enzyme molecule is a tetramer of the alpha 2 beta 2 type. The molecular weights of the alpha- and beta- subunits determined by polyacrylamide gel in the presence of sodium dodecyl sulfate are 52,000--56,000 and 27,000--29,000, respectively. Transketolase contains about two moles of TPP per mole of protein and does not require metal ions for its catalytic activity.