RESUMO
Different components of the renin-angiotensin system (RAS), whose content and activity are predetermined by local factors, are generated in the ocular tissue structures. The local eye RAS plays an important role in pathogenesis of different eye diseases and in the local manifestations of general pathological processes. Therefore, a study of the eye RAS components in norm and in disease contributes to understanding the pathogenesis of eye diseases and opens up new possibilities for an adequate treatment. The RAS components in the lacrimal fluid can be an important characteristics of such diseases like keratitis, diabetic retinopathy etc.
Assuntos
Oftalmopatias/etiologia , Olho/metabolismo , Sistema Renina-Angiotensina/fisiologia , Bradicinina/fisiologia , Retinopatia Diabética/etiologia , Retinopatia Diabética/metabolismo , Oftalmopatias/metabolismo , Humanos , Ceratite/etiologia , Ceratite/metabolismo , Lágrimas/metabolismoRESUMO
The kinetic behavior of proteolytic enzymes immobilized in thermosensitive hydrogels was studied at the phase transition (collapse) of the carriers. The dependence of the activity of immobilized enzymes on the state of the matrix allows the use of the hydrogel phase transition to regulate the activity of immobilized enzymes. Several cases of such regulation were demonstrated.
Assuntos
Resinas Acrílicas/química , Endopeptidases/metabolismo , Enzimas Imobilizadas/metabolismo , Fosfatase Alcalina/química , Fosfatase Alcalina/metabolismo , Quimotripsina/química , Quimotripsina/metabolismo , Endopeptidases/química , Estabilidade Enzimática , Enzimas Imobilizadas/química , Géis , Concentração de Íons de Hidrogênio , Especificidade por Substrato , Temperatura , Urease/química , Urease/metabolismoRESUMO
The structure of the conjugate of Bowman-Birk soybean proteinase inhibitor (BBI) with the block copolymer of ethylene oxide and propylene oxide (proxanol) containing five moles of proxanol per mole of protein, has been studied. Data from reverse phase hydrophobic HPLC suggest that the conjugate is less hydrophobic compared to native BBI. A shift of the second derivative UV absorption spectrum for the conjugate towards the shortwave region indicates a greater accessibility of the Tyr-59 residue localized in the interdomain region of the BBI molecule for the solvent. It has been assumed that the conjugate-induced increase in Ki for chymotrypsin may be due to both disturbances in the intact structure of the interdomain region of BBI and screening of the anti-chymotrypsin reactive center as a result of hydrophobic interactions of propylene oxide blocks of proxanol with exposed hydrophobic groups around the reactive center. Supporting evidence in favour of BBI molecule hydrophilization as a result of modification by proxanol can be derived from decreased conjugate penetration into intestinal epithelial cells as well as from the slow elimination of the conjugate from mouse blood stream.
Assuntos
Polietilenos/química , Polipropilenos/química , Inibidor da Tripsina de Soja de Bowman-Birk/química , Animais , Cromatografia Líquida de Alta Pressão , Quimotripsina/antagonistas & inibidores , Quimotripsina/metabolismo , Masculino , Camundongos , Estrutura Molecular , Polietilenos/farmacologia , Polipropilenos/farmacologia , Espectrofotometria Ultravioleta , Inibidor da Tripsina de Soja de Bowman-Birk/sangue , Inibidor da Tripsina de Soja de Bowman-Birk/farmacologiaRESUMO
A new method for determining the solvent accessibility of tyrosine and tryptophan residues in proteins from the wavelengths of absorption peak maxima in secondary derivatives of UV absorption spectra has been developed. Analytical expressions for calculating the number of groups in latent and exposed states of amino acid residues in protein globules were obtained on the basis of the previously elaborated mathematical model of spectral changes observed during the transition between those respective states. The new procedure was used to analyze sixteen proteins and showed a good correlation between the experimental results and literary data.
Assuntos
Proteínas/química , Triptofano/análise , Tirosina/análise , Modelos Teóricos , Solventes , Espectrofotometria UltravioletaRESUMO
Cathepsin G stimulates the hydrolysis of elastin from bovine neck ligament catalyzed by human leukocyte elastase. Stimulation factor depends on the ratio of the enzyme concentrations and ionic strength and equals 1.0-2.0. The classical Bowman-Birk inhibitor from soya retards strongly the hydrolysis of elastin catalyzed by leukocyte elastase, cathepsin G and the mixture of both. The inhibitory effect is practically unaffected by the adsorption of the enzymes on elastin, prolongation of the enzymatic reaction and ionic strength.
Assuntos
Catepsinas/metabolismo , Elastina/antagonistas & inibidores , Elastase de Leucócito/metabolismo , Leucócitos/enzimologia , Elastase Pancreática/metabolismo , Inibidor da Tripsina de Soja de Bowman-Birk/farmacologia , Sequência de Aminoácidos , Animais , Catálise , Catepsina G , Bovinos , Humanos , Hidrólise , Dados de Sequência Molecular , Concentração Osmolar , Serina EndopeptidasesRESUMO
Functions of proteinase inhibitors, connected with their ability to normalise proteolysis, are reviewed briefly. Arguments are suggested on favour of using the inhibitors as drugs for treatment of some diseases.
Assuntos
Inibidores de Proteases/farmacologia , Animais , Endopeptidases/metabolismo , Humanos , Hidrólise , CinéticaRESUMO
Isolation of the proteinases inhibitors, available for medicinal purposes, was described, where the inhibitor of the Kunitz type was obtained from bovine pancreas and the inhibitor of the Bowman-Birk type from soybeans. Screening of the immobilization procedures was carried out, which enabled the authors to produce the polymeric conjugates of the proteinase inhibitors exhibiting the maximal rate of activity against pancreatic proteinases and granulocyte elastases. Pharmacokinetics of the proteinase inhibitors obtained was studied. High molecular derivatives of the inhibitors from the bovine pancreas circulated in rat blood in larger quantities and longer, their total clearance was 5 times than native inhibitor preparations. The preparations containing these inhibitors from bovine pancreas exhibited a high therapeutic efficiency in treatment of rats with hemorrhagic pancreatitis and acute liver failure in rabbits.
Assuntos
Aprotinina/farmacologia , Inibidor da Tripsina de Soja de Bowman-Birk/farmacologia , Sequência de Aminoácidos , Animais , Aprotinina/isolamento & purificação , Aprotinina/uso terapêutico , Bovinos , Cromatografia por Troca Iônica , Humanos , Falência Hepática Aguda/tratamento farmacológico , Dados de Sequência Molecular , Pancreatite/tratamento farmacológico , Coelhos , Ratos , Inibidor da Tripsina de Soja de Bowman-Birk/isolamento & purificação , Inibidor da Tripsina de Soja de Bowman-Birk/uso terapêuticoRESUMO
A kinetic study of the interaction of the classical Bowman-Birk type soybean inhibitor (BBI 2-IV) with human granulocyte alpha-chymotrypsin and cathepsin G has been carried out. The K(a) values for the inhibitor-proteinase systems--alpha-chymotrypsin and cathepsin G (2.0 x 10(5) and 6.4 x 10(6) M-1 s-1, respectively) have been established.
Assuntos
Catepsinas/antagonistas & inibidores , Quimotripsina/antagonistas & inibidores , Granulócitos/enzimologia , Inibidor da Tripsina de Soja de Bowman-Birk/farmacologia , Sequência de Aminoácidos , Sítios de Ligação , Catepsina G , Humanos , Cinética , Dados de Sequência Molecular , Serina EndopeptidasesRESUMO
A quantitative method is suggested for estimating the structure and conformational stability of proteins based on the individual absorbance of Tyr residues in the second derivative UV spectra. Subtilisins Carlsberg, BPN' and 72 were chosen as the model proteins. The values of the increase of the Tyr absorption at 282.3 nm upon the total denaturation of the proteins made it possible to calculate the number of the exposed and "buried" tyrosine residues in the native proteins. A mathematical model of spectrum changes during the transition of Tyr residues from the "buried" to exposed form is suggested. The method is useful for the determination of the denaturation constants of proteins bearing "buried" tyrosine residues.
Assuntos
Conformação Proteica , Espectrofotometria Ultravioleta/métodos , Subtilisinas/química , Modelos Teóricos , Desnaturação Proteica , Tirosina/químicaRESUMO
Catalytic activity of alpha-chymotrypsin preparations covalently included in the matrix of the poly-N-isopropylacrylamide gel does not follow Arrhenius equation above the low critical temperature of the polymer dissolution. Starting from this temperature, at which the changes of polymer structure takes place (hydrophobization), the temperature increase results in a rate lowering for the chemical reaction catalyzed by the enzyme. This phenomenon is reversible. A correlation between temperature dependence of the immobilized alpha-chymotrypsin activity and the dehydration degree of the carrier is observed. The decrease of the water content in the matrix causes a change of the substrate specificity of the immobilized alpha-chymotrypsin.
Assuntos
Quimotripsina/metabolismo , Enzimas Imobilizadas/metabolismo , Acrilamidas , Catálise , Cinética , Polímeros , Especificidade por Substrato , Temperatura , ÁguaRESUMO
A one-step procedure for human leukocyte elastase purification using an affinity adsorbent based on protein soybean Bowman-Birk proteinase inhibitor has been developed. The leukocyte elastase was purified 70-fold with a 70-100% yield. The enzyme preparations did not contain cathepsin G and displayed a high specific activity. The soybean Bowman-Birk type inhibitor effectively inhibited the elastin hydrolysis by leukocyte elastase both when the enzyme and the inhibitor were simultaneously added to the substrate and after preliminary elastase adsorption on elastin. The inhibitory effect was preserved at high degrees of elastin hydrolysis.
Assuntos
Elastina/metabolismo , Elastase Pancreática/isolamento & purificação , Inibidor da Tripsina de Soja de Bowman-Birk/metabolismo , Marcadores de Afinidade , Sequência de Aminoácidos , Catálise , Cromatografia de Afinidade , Eletroforese em Gel de Poliacrilamida , Humanos , Hidrólise , Elastase de Leucócito , Dados de Sequência Molecular , Elastase Pancreática/metabolismoRESUMO
A classical soybean inhibitor of the Bowman-Birk type (BBI) with a copolymer of ethylene oxide and propylene oxide (PE) has been synthesized. The BBI-PE conjugate contain five covalently bound polymeric chains per one protein molecule and retains its capacity to inhibit trypsin (Ki = 10(-10) M), alpha-chymotrypsin (Ki = 7 x 10(-8) M) and human granulocyte elastase (Ki = 3 x 10(-8) M). The preservation of the antiproteinase activity in the antichymotrypsin center creates a prerequisite for the manifestation of the anticarcinogenic effect of the inhibitor.
Assuntos
Compostos de Epóxi/metabolismo , Óxido de Etileno/metabolismo , Inibidor da Tripsina de Soja de Bowman-Birk/metabolismo , Quimotripsina/antagonistas & inibidores , Elastase de Leucócito , Elastase Pancreática/antagonistas & inibidores , PolímerosRESUMO
A classical soybean inhibitor (Bowman-Birk inhibitor, BBI 2-IV) and two high molecular weight glycine-enriched inhibitors of the same type (3-II and 4-II) have been isolated, purified to homogeneity and characterized. All of the BBI isoforms have been found to effectively inhibit cathepsin G and human granulocyte elastase. The constants for leucocyte cathepsin G inhibition by classical BBI 2-IV (Ki = 1.2 x 10(-9) M) and high molecular mass BBI 3-II (Ki = 8.0 x 10(-8) M) as well as for leucocyte elastase inhibition by high molecular mass BBI 3-II (Ki = 1.1 x 10(-7) M) have been determined.
Assuntos
Catepsinas/antagonistas & inibidores , Granulócitos/enzimologia , Elastase Pancreática/antagonistas & inibidores , Inibidor da Tripsina de Soja de Bowman-Birk/farmacologia , Aminoácidos/análise , Cromatografia em Gel , Cromatografia por Troca Iônica , Humanos , Cinética , Inibidor da Tripsina de Soja de Bowman-Birk/química , Inibidor da Tripsina de Soja de Bowman-Birk/isolamento & purificaçãoRESUMO
Three active-site-acylated derivatives of the activator plasmin-streptokinase complex have been synthesized: n-anisoyl-, n-trans-(N,N,N-trimethylamino)-cinnamoyl- and n-guanidine-benzoyl-plasmin-streptokinase. Their diacylation rate constants were 4.2 x 10(-4), 2.0 x 10(-4) and 0.6 x 10(-4) s-1, respectively. Kinetics of lysis of fibrin clots, containing plasminogen or plasminogen and alpha 2-antiplasmin, by acylplasmin, by a free activator complex and by two acylated activator complexes has been studied. It is shown that in the presence of zymogen and inhibitor the effect of acylactivator, as a fibrinolytic, is 163 times more effective than that of acylenzyme and the fibrinolytic response increases with the doze of acylactivator. The rate of fibrinolysis by a free plasmin-streptokinase complex was higher without the inhibitor than that of fibrinolysis by its acylated derivatives; fibrinolytic action of acylactivators was more effective in the presence of the inhibitor.
Assuntos
Anistreplase/metabolismo , Fibrinólise , Acilação , Antifibrinolíticos/metabolismo , Sítios de Ligação , Humanos , Cinética , Plasminogênio/metabolismoRESUMO
Kinetics of lysis of fibrin clots from the human, guinea pig, rat and rabbit blood plasma by two active-site-acylated derivatives of the activator plasmin-streptokinase complex with different reaction rate constants has been studied in vitro. It is found that lysis of blood plasma clots in guinea pig is most similar to that of man. Acyl activator dose being increased, the lysis of a plasma clot in guinea pig is accelerated. Two acyl activators exhibit higher fibrinolytic-efficiency as compared to a free activator. Experiments carried out in vivo on guinea pigs with thrombosis show that acyl activators, in contrast to nonmodified plasmin-streptokinase complex induce the less system activation of fibrinolysis and the less fibrinogenolysis.
Assuntos
Anistreplase/metabolismo , Fibrinólise/efeitos dos fármacos , Fibrinolíticos/farmacologia , Acilação , Animais , Sítios de Ligação , Cobaias , Humanos , Cinética , Coelhos , RatosRESUMO
In the experiments on guinea-pigs with venous thrombosis there were studied the fibrin- and thrombolytic effects of streptokinase, the plasmin-streptokinase complex and the acylated derivatives of the complex with various rates of reactivation. It was established that the acylated derivatives of the plasmin-streptokinase complex possess greater stability in the blood flow and lead to more prolonged stimulation of fibrinolysis at less magnitude of its systemic activation. Due to this the acylated derivatives of the plasmin-streptokinase complex produce less pronounced fibrinogenolysis. In connection with a high affinity to fibrin their thrombolytic action does not depend on the systemic activation of fibrinolysis.
Assuntos
Anistreplase/farmacologia , Fibrinólise/efeitos dos fármacos , Ativadores de Plasminogênio/farmacologia , Estreptoquinase/farmacologia , Animais , Anistreplase/síntese química , Anistreplase/uso terapêutico , Modelos Animais de Doenças , Avaliação Pré-Clínica de Medicamentos , Sinergismo Farmacológico , Cobaias , Ativadores de Plasminogênio/síntese química , Ativadores de Plasminogênio/uso terapêutico , Estreptoquinase/síntese química , Estreptoquinase/uso terapêutico , Trombose/sangue , Trombose/tratamento farmacológico , Trombose/etiologiaRESUMO
Kinetics of fibrinolysis by plasmin and plasmin streptokinase complex have been studied using fibrin gels formed from purified fibrin and human blood plasma. The gels were placed into buffer or blood plasma. The contributions of plasminogen and alpha 2-antiplasmin present or absent in both phases to the kinetics of fibrinolysis were quantitatively estimated. In the complex catalyzed fibrinolysis, plasminogen activation reaction dominated whereas in plasmin-catalyzed fibrinolysis, the inhibitor involved reaction, suppressing the process, prevailed.
Assuntos
Fibrinolisina/metabolismo , Fibrinólise/fisiologia , Estreptoquinase/metabolismo , Esterases/metabolismo , Fibrinolisina/antagonistas & inibidores , Géis , Humanos , Técnicas In Vitro , CinéticaRESUMO
The interactions of plasmin and plasmin-streptokinase equimolar complex with a number of protein and low-molecular weight substrates as well as protein inhibitors have been examined. It was concluded that the above interactions entail structural changes in the complexes formed, which trigger the activator, increase the rate constants of low molecular weight substrates but create steric hindrances to the interaction with protein substrates and inhibitors.
Assuntos
Fibrinolisina/metabolismo , Proteínas/metabolismo , Estreptoquinase/metabolismo , Caseínas/metabolismo , Catálise , Esterases/metabolismo , Fibrina/metabolismo , Fibrinolisina/antagonistas & inibidores , Humanos , Peso Molecular , Especificidade por SubstratoRESUMO
The binding of the angiotensin-converting enzyme from bovine lung on BrCN-activated Sepharose, CH- and AH-Sepharoses as well as on AH-Sepharose via the carbohydrate fragment of the glycoprotein molecule modulates the possible microenvironment of the enzyme in vivo. It has been shown that the close interaction of the enzyme with the carbohydrate matrix may increase the absolute values of catalytic constants for the hydrolysis of certain substrates. The binding of the angiotensin-converting enzyme to the matrices markedly changes the enzyme activation by chloride ions by causing a shift in the activity optima towards lower activator concentrations.