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M A Mateescu

Publications and source records attributed to M A Mateescu.

At least 19 recordsLinked to original sources
PubMed1996

Extended substrate specificity of serum amine oxidase: possible involvement in protein posttranslational modification.

The capacity of bovine serum amineoxidase (SAO) to oxidize free amino groups of nonconventional substrates, such as polylysine (up to 50 kDa) and some proteins as lysozyme and ribonuclease A, is described. The oxidation was quantified from the amount of H2O2 and NH3 enzymatically produced by SAO. Kinetic analysis indicated a stereospecific preference for L-configuration. Maximal oxidation rate was obtained with poly-L-lysine (9.6 kDa). After 10 h of incubation at 37 degrees C, the poly-L-lysine was partially oxidized generating 1.5 moles of H2O2 by one mole of polylysine. Denatured SAO presented very low oxidation rates with the mentioned substrates.

Amine Oxidase (Copper-Containing)↗
PubMed1996

Modulation of K+ channel currents by serum amineoxidase in neurons.

The influence of bovine serum amineoxidase (SAO), a circulating copper-enzyme, on neuronal K+ channels is described. Bovine SAO enhanced K+ channel currents in N1E-115 neuroblastoma cells in a time-dependent manner. Unlike ceruloplasmin (another copper-protein, shown as depolarizing factor in neurons), SAO had no effect on resting potential of neurons. However, pretreatment of cells with SAO inhibited ceruloplasmin-induced membrane depolarization. Although ceruloplasmin alone inhibited K+ channel currents, it further enhanced K+ channel currents in the presence of SAO. Therefore, SAO may be another endogenous modulator of neuronal K+ channels with effect and mechanisms different from those of ceruloplasmin.

Amine Oxidase (Copper-Containing)↗
PubMed1996

Comparative antioxidant and cardioprotective effects of ceruloplasmin, superoxide dismutase and albumin.

The antioxidant effects of ceruloplasmin (CAS 9031-37-2) against oxygen free radicals (.O2-, .OH, 1O2) and their by-products (H2O2, HOCl), generated by electrolysis of Krebs-Henseleit buffer, were determined in vitro by the DPD (N,N-diethyl-p-phenylenediamine) colorimetric method and ex vivo by quantifying cardiodynamic variables of the isolated perfused rat heart. Purified ceruloplasmin (1 mumol/l) displayed a high antioxidant capacity in vitro (89.2%), while the scavenging capacity of superoxide dismutase (SOD) in equimolar concentrations was 38.1%. A relatively high scavenging activity (72.1%) was observed with bovine serum albumin (BSA). A control group of Langendorff isolated rat hearts (n = 8) was submitted to electrolysis (10 mA, for 1 min) without treatment, whereas the treated groups were perfused with ceruloplasmin, SOD or BSA (1 mumol/l) in the inflow cannula for 5 min before, during, and 5 min after electrolysis. The cardioprotective effect afforded by ceruloplasmin (83-89%) was higher than that observed with the same optimal dose of 1 mumol/l SOD (20-45%). With BSA, no protection was observed ex vivo. Particularities in scavenging specificities and mechanisms seem to explain the important differences between in vitro and ex vivo antioxidant capacities for these proteins.

Animals↗
PubMed1996

Class III antiarrhythmic effects of ceruloplasmin on rat heart.

Recently it has been shown that ceruloplasmin presents a protective action against reperfusion-induced arrhythmias in the isolated perfused rat heart, an effect that is lost when the protein is denaturated by heat. The present study was carried out to see whether ceruloplasmin can alter electrophysiological properties such as ventricular effective refractory periods, conduction time, and action potential duration calculated at 50, 75, and 90% levels of repolarization (APD50, APD75, APD90). To check the specificity of the electrophysiological effects of ceruloplasmin, we have also compared them with those of heat-denatured ceruloplasmin, superoxide dismutase, catalase, deferoxamine, and albumin. In isolated rat hearts, ceruloplasmin (0.25-3 microM) (n = 8 for each concentration) was shown to increase the effective refractory period in a concentration-dependent manner by 26 to 89%. Conduction time was not significantly altered. Heat-denatured ceruloplasmin (0.50-3 microM) (n = 8 for each concentration) increased the effective refractory period by 33 to 70% and did not affect the conduction time. In contrast, superoxide dismutase (1-4 microM), catalase (1-2 microM), deferoxamine (500 microM-1 mM), and albumin (1-4 microM) (n = 8 for each substance and for each concentration) had no significant effect on effective refractory period and conduction time at any dose, suggesting that the ceruloplasmin effect might be specific. In rat ventricular preparations, ceruloplasmin (1 microM) also induced a constant prolongation of APD50 (52%), APD75 (64%), and APD90 (41%) after 15 min of infusion (n = 6). The prolongation of effective refractory period and of action potential duration, by native and heat-denatured ceruloplasmin, suggests that this substance has specific class III effects, although this cannot entirely account for its antifibrillatory action at reperfusion in isolated rat hearts.

Action Potentials↗
PubMed1995

Ceruloplasmin: an endogenous depolarizing factor in neurons?

The biological effects of ceruloplasmin have been exclusively ascribed to its roles as a copper carrier and an antioxidant. Although neuronal involvement of ceruloplasmin is closely related to aging and certain neuronal disorders, neuronal effects of ceruloplasmin are unknown and the possible modulation of membrane potential and ion channels by ceruloplasmin has not been investigated. In the present study, the membrane electrical properties of neuroblastoma cells in the presence of ceruloplasmin were studied using the patch-clamp technique. Ceruloplasmin induced a rapid and sustained membrane depolarization. This capacity of ceruloplasmin was abolished either when the copper was removed from ceruloplasmin or when ceruloplasmin was heat-inactivated. The depolarizing effect of ceruloplasmin was not due to an enhanced Ca2+ or Na+ influx but it seemed to result from a reduced K+ efflux since ceruloplasmin significantly inhibited a TEA-sensitive delayed rectifier K+ channel. To our knowledge, this is the first report which indicates that ceruloplasmin is an endogenous neuronal depolarizing factor.

Calcium↗
PubMed1995

Antiarrhythmic effects of ceruloplasmin during reperfusion in the ischemic isolated rat heart.

The ability of ceruloplasmin, an important serum antioxidant, to reduce the vulnerability of the isolated rat heart to reperfusion arrhythmias has been investigated. Bovine plasma ceruloplasmin was purified by chromatography on aminoethyl-agarose. Isolated rat hearts were submitted to 15 min of regional ischemia and 10 min of reperfusion. The dose-effect relationship and the role of ceruloplasmin conformational integrity in cardioprotection were established by treatment of ischemic hearts with ceruloplasmin at various concentrations (0.25, 0.5, 1, and 2 microM) and at different degrees of conformational integrity (A610/A280 = 0.02, 0.04, and 0.06), 5 min before reperfusion. Deferoxamine (20-500 microM) was used as a positive control. As negative controls we used chemically inactivated ceruloplasmin (1 microM), heat-denatured ceruloplasmin (1 microM), and albumin (1-4 microM). In the control group during the first 5 min of reperfusion, the incidence of total ventricular fibrillation was 100% and of irreversible ventricular fibrillation was 83%. The incidence of reversible and irreversible ventricular fibrillation was significantly decreased in the ceruloplasmin-treated groups in both a dose and molecular integrity dependent manner. Ceruloplasmin had no effect on the incidence of ventricular tachycardia. Deferoxamine reduced the incidence of ventricular fibrillation to the same degree as ceruloplasmin but at concentrations much higher than those of ceruloplasmin. Chemically inactivated ceruloplasmin, heat-denatured ceruloplasmin, and albumin had no protective effects on reperfusion-induced arrhythmias.

Animals↗
PubMed1995

Protection of myocardial tissue against deleterious effects of oxygen free radicals by ceruloplasmin.

This study describes the carioprotective effect of ceruloplasmin (CAS 9031-37-2) against oxygen free radical injury, as indicated by several biochemical indicators and some cardiodynamic variables. Isolated rat hearts (n = 4-8, p < 0.05, for each experimental point) in Langendorff preparation were exposed to oxygen free radicals generated by electrolysis (10 mA) in the absence and the presence of 0.25 mumol/l purified ceruloplasmin and denaturated ceruloplasmin, in Krebs-Henseleit perfusion solutions. Biochemical indicators (noradrenaline, malondialdehyde, creatine-kinase, lactate dehydrogenase, aspartate aminotransferase, Ca2+ and Mg2+) as well as the electrocardiogram and the left ventricular pressure (LVP), were altered by oxygen free radicals formation, denoting major cellular and tissular damages in the nontreated hearts. Ceruloplasmin exhibited a cardioprotective effect and prevented the oxygen free radical-induced release of noradrenaline, indicating that it can also protect the sympathetic nerve endings from oxygen free-radical injury. Purified ceruloplasmin, a circulating extracellular antioxidant and oxygen free radical scavenger, seems to be an effective heart protective agent against myocardial and neuronal injuries generated by oxygen free radicals.

Animals↗
PubMed1994

Joint chromatographic purification of bovine serum ceruloplasmin and amineoxidase.

A purification procedure leading to a joint separation of two serum copper-enzymes: ceruloplasmin (EC 1.16.3.1) and amineoxidase (EC 1.4.3.6), is described. Both enzymes are obtained in electrophoretically homogeneous form and their specific activities are higher than those obtained by previously described purification techniques. Two common steps: precipitation of bovine plasma proteins with ammonium sulphate (at 35% and 55% saturation) followed by column chromatography on AE-Agarose (obtained by treatment of agarose beads with 1-chloro-2-ethylamine), lead to an electrophoretically homogeneous ceruloplasmin. At the same time, the ceruloplasmin-free protein preparation eluted in a first peak, following further Q-Sepharose and Con A-Sepharose chromatography, leads to purified bovine serum amine oxidase (BSAO) with an improved yield. The emphasis was given to a mutual improving effect as a consequence of the integration of the two enzymes purification procedures.

Amine Oxidase (Copper-Containing)↗
PubMed1993

Cytotoxicity and kinetic analysis of purified bovine serum amine oxidase in the presence of spermine in Chinese hamster ovary cells.

Bovine serum amine oxidase (BSAO, EC 1.4.3.6) catalyzes the oxidative deamination of polyamines giving rise to the corresponding aldehydes, ammonia and hydrogen peroxide (H2O2). This study demonstrates that amine oxidase (BSAO) purified from bovine serum and exogenous spermine caused cytotoxicity in Chinese hamster ovary (CHO) cells. Cytotoxicity occurred when cells were exposed to BSAO (0.0164-16.4 micrograms/ml) in the presence of spermine (1.9-340 microM). BSAO and spermine alone were not toxic at these concentrations. Cytotoxicity was dependent on the concentration of spermine and on the incubation time, and was also accelerated at 42 degrees C relative to 37 degrees C. Kinetic analysis of the enzymatic reaction, as a function of spermine concentration, showed Michaelis-Menten saturation kinetics. The apparent Vmax increased from 19.1 +/- 0.4 microM min-1 at 37 degrees C to 23.0 +/- 0.3 microM min-1 at 42 degrees C. The apparent Km decreased from 25.5 +/- 2.6 microM at 37 degrees C to 17.7 +/- 1.3 microM at 42 degrees C. Catalase inhibited cytotoxicity, suggesting that H2O2 was partially responsible for cytotoxicity. This work shows that the oxidation products of polyamines, rather than the polyamines themselves, are responsible for cytotoxicity in mammalian cells. The significance of this study is that amine oxidases could have therapeutic potential in cancer treatment regimens and a beneficial effect is likely when the enzyme is used together with clinical hyperthermia.

Amine Oxidase (Copper-Containing)↗
PubMed1992

Fast separation of macrophages by retention on cross-linked amylose and release by enzymatic amylolysis of the chromatographic material.

Macrophages from mice peritoneal exudate were isolated on basis of specific adherence on epichlorohydrin cross-linked amylose (CLA), a chromatographic gel presenting a high susceptibility to advanced amylolysis with alpha-amylase. The cell suspension, containing predominantly macrophages and lymphocytes, was applied onto the column and incubated for 30 min at 37 degrees C for the adherence of macrophages. After this interval the non-adherent cells were eluted with buffered medium and the CLA support was incubated in the column with an alpha-amylase-buffered solution liquefying the matrix and releasing, in situ, the adherent cell population containing 90% macrophages with a viability higher than 90%.

Amylose↗
PubMed1992

Specific temperature dependence of diamine oxidase activity and its thermal stability in the presence of polyvinylalcohol.

An inflexion point on the dependence of the swine kidney diamine oxidase activity upon the temperature was found at 40-43 degrees C, suggesting a conformational transition. The activation energies with putrescine as substrate calculated from the Arrhenius plots were 38.23 kcal/mol for the temperature interval 25-40 degrees C and only 15.14 kcal/mol for the range 45-60 degrees C. These values suggest two different conformations, one corresponding to the interval below 40 degrees C and another one between 43-60 degrees C, with an intermediate transitory form corresponding to the inflexion point at 40-43 degrees C. For various temperature decades within 10-60 degrees C, peculiar Q10 values in the range 1.37-3.00 (differing from the usual value Q10 = 2), were obtained. The non-strictly Arrhenius curves, the activation energies and the inflexion point were quite similar with and without 0.05% polyvinylalcohol. This particular temperature effect found for swine kidney diamine oxidase is similar to the one reported for bovine serum amine oxidase. An increased enzyme thermal stability was obtained in the presence of high molecular weight polyvinylalcohol.

Amine Oxidase (Copper-Containing)↗
PubMed1991

Protective effects of ceruloplasmin against electrolysis-induced oxygen free radicals in rat heart.

The potentially injurious effects of oxygen-derived free radicals (OFR) on the myocardium can be prevented in part by pretreatment with OFR scavengers or antioxidants. Since ceruloplasmin (CP) has been shown to possess potent antioxidant activity and scavenge a variety of OFR in vitro, we have undertaken to study its protective effects against myocardial injury induced by OFR. CP was freshly purified by a fast method that minimized proteolytic enzyme degradation. Free radicals were generated by the electrolysis (10 mA DC current for 1 min) of a Krebs-Henseleit solution perfusing an isolated rat heart preparation under constant pressure conditions. CP (0.25 microM) afforded 80 and 63% protection (n = 8, p less than 0.05), respectively, against the deleterious effects of electrolysis-induced OFR on left ventricular pressure and coronary flow. The increase in left ventricular end diastolic pressure used here as an index of heart failure did not occur in the presence of 0.25 microM CP. Moreover, CP significantly reduced the increase of norepinephrine washout in the effluent perfusate after electrolysis suggesting a protection against free radical-induced injury to sympathetic nerve endings.

Animals↗
PubMed1989

Peculiar effects of temperature and polyvinylalcohol on the activity of bovine serum amine oxidase.

An inflexion point of enzyme activity at 38 - 42 degrees C of the bovine serum amineoxidase was found. This result, associated with non-strict Arrhenius curves and slightly different activation energies in various temperature intervals, suggests some conformational transitions at the mentioned temperatures. The high molecular weight polyvinylalcohol (100,000 Da) generated an activatory effect and a sigmoidal (non-Michaelis) curve of the dependence of the activity on the substrate concentrations, while the low molecular weight polyvinylalcohol (20,000 Da) does not produce this effect. The different ratio of the two types of polyvinylalcohol/enzyme monomer sizes is considered to be responsible for these different effects on the enzyme kinetics.

Amine Oxidase (Copper-Containing)↗
PubMed1988

Reexamination of spectroscopic properties of ceruloplasmin freshly isolated with a novel very rapid single-step procedure.

A novel, single-step, chromatographic procedure for the purification of ceruloplasmin is described. The procedure consists of a single chromatographic step, leading in approximately 5 hours from 2 liters of plasma to an electrophoretically homogeneous ceruloplasmin preparation which exhibits different spectroscopic properties with respect to the protein obtained with more lengthy, currently available procedures. The method is suitable for either small or large scale purification from various vertebrate plasma.

Animals↗
PubMed1985

All-reagent test tablets and method for rapid and selective alpha-amylase iodometric determination.

The new type of test tablets (Iodocrom) for alpha-amylase assay contain crosslinked (CL)-amylose or CL-starch (specific substrates for alpha-amylase only) and the reagent (KIO3/KI) generating iodine (in acidic medium, when the reaction is stopped). The method--amyloclastic in nature--is based on selective action of alpha-amylase on the CL-substrate liberating soluble polysaccharide chains large enough and in a conformation suitable to allow the formation of iodine inclusion complexes. Unlike the classical iodometric methods, the reaction is followed by an increase in iodine complex blue color. The method has some common points with the well-known chromogenic (e.g., Phadebas) methods. Both use insoluble substrates which are not susceptible to attack by exoamylases and in both cases the enzymatic reaction is followed by the release of soluble products. The amounts of these released chains and the absorbances of their inclusion complexes with iodine are in a linear dependence with the enzyme concentration (activity).

Humans↗