1,720,986 research outputs found
POWERFUL INHIBITOR OF GUANINE DEAMINASE
No full textThe synthesis of 9-(p-carbetoxyphenyl) guanine is reported. The assays carried out on guanine deaminase from rat and rabbit liver and pig brain show that this compound is a powerful inhibitor. The compound has a Ki = 5 uM for the enzyme from pig brain. The use of the inhibitor for the synthesis of a specific adsorbent for guanine deaminase was studied
ADENOSINE-DEAMINASE FROM HUMAN LYMPHOCYTES AND ERYTHROCYTES - PURIFICATION AND SOME PROPERTIES
No full textGENERAL METHOD OF PURIFICATION OF ADENOSINE DEAMINASE BY AFFINITY CHROMATOGRAPHY
No full textAffinity chromatography has been used to purify adenosine deaminase from various sources: calf spleen, calf intestinal mucosa, chicken duodena and human erythrocytes. For this purpose a specific inhibitor, 9-(p-aminobenzyl) adenine, was synthesized and covalently joined to agarose. Adenosine deaminase is selectively retained by such an inhibitor-resin when highly impure solutions are chromatographed through it. After elution from the resin with guanylurea, a competitive inhibitor, the enzyme is homogeneous and can be recovered in yields of 80 percent or more and the same number of multiple forms of the enzyme is present in the purified preparation and in the crude extract
DIGESTION OF INSULIN DERIVATIVES WITH SUBTILISIN - KINETIC STUDY
No full textNative, denatured, performic acid-oxidized or S-sulfo insulin and S-sulfo or performic acid-oxidized A- and B-chains were digested with subtilisin type Carsberg. The proteolysis was followed by measuring the uptake of alkali through autotitration. The kinetic study shows the existence of 2 first-order reaction classes which differ markedly in rate constant. The number of bonds split with fast and with slow reactions has been calculated. Only one of a total of 12 cleavable bonds in native insulin is opened by fast reaction. In the denatured protein the number of bonds split by the fast reaction increases to 4 and in the oxidized and S-sulfo protein 3 bonds are cleaved, while the slow cleavable bonds number 2 and 7, respectively, The kinetic study of the proteolysis of S-sulfo A-chain and of oxidized or S-sulfo B-chain shows that two bonds are split in A-chain with the fast and slow reactions, while in B-chain only one of the six cleavable bonds is susceptible to fast attack
Production of ouabain-like factor in normal and ischemic rat heart
No full textEndogenous ouabain-like factor (OLF) has been detected in mammalian plasma, adrenal gland, and hypothalamus. We investigate whether cardiac tissue may also produce OLF. HPLC chromatographic separation of cardiac extracts showed that RIA-determined OLF activity coincided with the elution profile of exogenous ouabain and with the ability to inhibit 86Rb uptake in human erythrocytes. OLF activity was remarkably higher in excised hearts (3.94 +/- 0.84 pmol/g wet weight by RIA) than in rat blood (0.05 +/- 0.02 pmol/ml). Similar values were obtained in perfused working hearts, without significant changes over time from 5 to 30 minutes of aerobic perfusion. Significant OLF release in the perfusion buffer was also observed (0.54 +/- 0.05 pmoles over 30 minutes). In hearts subjected to 15 minutes of aerobic perfusion followed by 15 minutes of global myocardial ischemia OLF concentration was remarkably increased (8.59 +/- 1.13 versus 4.58 +/- 0.57 pmol/g wet weight by RIA, P < 0.01; an increase after ischemia was confirmed by the assay of 86Rb uptake). Our findings suggest that the rat heart is able to produce OLF, and that its concentration increases during ischemia. Myocardial OLF might modulate the Na/K-ATPase, producing relevant effects on ionic homeostasis and/or gene transcription
Further evidence for an endogenous digitalis-like compound in newborn and adult plasma detected by anti-ouaboin antiserum
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Cardioprotection by ouabain and digoxin in perfused rat hearts
No full textThis work was aimed at determining the cardioprotective effect of digitalis glycosides in rat heart, and to relate it with Na+, K+-ATPase inhibition and ERK1/2 activation. Isolated working rat hearts were perfused in the presence of ouabain or digoxin, which were used at concentrations ranging from 10(-8) to 10(-5) M. The hearts were then subjected to 30 minutes of global normothermic ischemia followed by 120 minutes of retrograde reperfusion; irreversible tissue injury was determined on the basis of triphenyltetrazolium chloride staining. Significant cardioprotection was observed with 10(-7) M and 10(-5) M ouabain (ischemic injury averaged 7.0 +/- 3.5% and 8.3 +/- 0.6% versus 37.3 +/- 2.0% in controls. P < 0.01 in each case). Hearts treated with digoxin showed decreased ischemic injury at 10(-6) M and 10(-5) M (18.0 +/- 1.5% and 14.2 +/- 1.0%, P < 0.01 versus control in both cases). In parallel experiments, ERK2 phosphorylation was increased by 10(-7) to 10(-5) M ouabain, while ERK1 and ERK2 phosphorylation was increased by 10(-6) to 10(-5) M digoxin. The cardioprotective effect was not related to Na+, K+-ATPase inhibition, since Rb+ uptake was not significantly different between control and treated hearts
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