Ioan Florea Dumitru

Activation by copper ions of mytilidases—acid proteolytic enzymes obtained from Mytilus galloprovincialis

Abstract 1. 1. Cu 2+ ions strongly activate acid proteases, purified from the hepatopancreas of Mytilus galloprovincialis . 2. 2. In the presence of the effector the first optimal pH is displaced from 1.5 to 1.85 and at high hemoglobin concentrations, inhibition occurs. 3. 3. Copper ions do not protect acid proteases from the denaturing effect of temperature, while hemoglobin has a heat-protector effect.

Decrease in yeast glucose-6-phosphate dehydrogenase activity due to oxygen free radicals

1. u.v. radiations and copper acetate, as free radical generating systems, determine a significant diminishing of glucose-6-phosphate dehydrogenase activity in the homogenates of Saccharomyces cerevisiae. 2. The inactivation is proportional to the concentration of the formed free radicals, existing a direct dependence on the action time of the free radicals generating systems and on the irradiation dose. The decrease of the enzyme catalytic activity is correlated with the increase of the malondialdehyde concentration. 3. The affinity for the substrate of the enzyme under the action of free radicals does not change significantly compared to the native enzyme: the Km value for NADP is halved, whilst that for glucose-6-phosphate remains unchanged. 4. The electrophoretic study shows evidence of five electrophoretic bands with enzymatic activity in the native extract and the disappearance of one molecular form under the free radical action.

Correlations between the activities of semen acid phosphatase and Ca+-dependent ATPase and age in different breeds of cocks

1. The present work aims to find a biochemical criterion for evaluating the evolution of sperm according to age through the study of the ATPase activity from the spermatozoa and the acid phosphatase from the seminal plasma of cocks from three different breeds. 2. The optimal parameters of action of the cock semen acid phosphatase and the Ca(2+)-dependent ATPase from the spermatozoa were studied. 3. The substrate specificity of the semen acid phosphatase and its inhibition by tartrate, fluoride, metavanadate, molybdate and Hg2+ were also studied. 4. The two enzymes were determined from the Sussex, Golden Cornish and Plymouth Rock breeds at different ages. 5. The data lead to the conclusion that some properties of bird spermatozoa are less influenced by breed while the acid phosphatase activity, secreted in the ductus deferens is a breed characteristic.

Spin-spin relaxation times in myocardial hypertrophy induced by endocrine agents in rat

Magnetic resonance techniques afford a significant advantage for noninvasive diagnosis of cardiovascular pathology. The purpose of our present study was to assay the proton nuclear magnetic resonance (1H-NMR) sensitivity in the differential diagnosis of certain endocrine cardiovascular complications. In this context, we investigated the water state and content in the hypertrophied myocardium. Male and female Wistar rats were treated with different hormones (hydrocortisone acetate, testosterone, estradiol, thyroid hormones) in combination with isoproterenol (a synthetic catecholamine that induces myocardial ischemia and hypertrophy). The animals were sacrificed after 20 days of treatment and samples of integral myocardium and left ventricular myocardium were analyzed on a1H-NMR AREMI spectrometer (0.6 T; proton resonance at 25 MHz). The estimation ofT2 was made by Carr-Purcell-Meiboom-Gill pulse sequence. The data were fitted to a bi-exponential curve, yielding short (T21) values forbound water and long (T22) values forfree water. In order to evaluate the myocardial hypertrophy, the following ratios were calculated: integral myocardium to body weight; left ventricle to body weight; left ventricle to integral myocardium. The first two ratios were also calculated for dried tissue, in order to estimate its contribution to myocardial hypertrophy. Our findings demonstrate that myocardial hypertrophy is associated with a decrease ofT22, as a consequence of the increase in the dried component (i.e. proteins) of the tissue, while the total tissue, while the total tissue water (H2Ot%, measured by gravimetry) was not significantly modified. Nevertheless, it is reasonable that the increase in the protein content would be proportional with the increase in H2Ot%. The decrease ofT21 seems to be proportional with the level of left ventricle hypertrophy in female groups. The1H-NMR measurements were much sensitive for the differential diagnosis of myocardial hypertrophy in the case of left ventricle.

Chromatographic purification, crystallization and study of vegetablel-alanine: 2-oxoglutarate-aminotransferase properties

l-Alanin-2 Oxoglutarataminotransferase aus Soya,Glycine hispida, wurde 230fach gereinigt und kristallisiert sowie einige physikalisch-chemische Eigenschaften (Michaelis Konstante, spezifische Wirkung, pH, Temperatureinfluss, ionale Wirkungen und Metaboliten) wurden studiert.

Cock seminal plasma acid phosphatase: Active site directed inactivation, crystallization and in vitro denaturation-renaturation studies

1. Seminal plasma acid phosphatase from the mini Rock cocks was purified on a Sepharose 6B column and was not homogeneous on polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate. Its stability in time was also determined. 2. In the same time, the enzyme was crystallized in both ethanol and ammonium sulfate and this is also an evidence that this acid phosphatase was obtained in an advanced grade of purification but is present in a complex with some quantities of other proteins. 3. It was inactivated by iodoacetate to a degree consistent with the modification of an active site residue. DTNB and thiosulfate also inhibited this enzyme. 4. The enzyme was sensitive to 6 M guanidinum hydrochloride which in the presence and absence of 0.25 M mercaptoethanol produces a deep loss of activity. After dialysis the activity was increased during the first 10 days up to 66.2% of the initial one. 5. In the presence of molar concentration of mercaptoethanol, the enzyme activity is deeply decreased, but it is partially restored after 120 hr when 1 microM CuCl2 is added.

A new proteolytic enzyme isolated from Mytilus galloprovincialis: Mytilidase. Purification, crystallization and partial characterization

Abstract 1. 1. A procedure for the advanced purification of acid protease(s) obtained from the hepatopancreas of the sea mussel, Mytilus galloprovincialis, is described. 2. 2. Proteolytic activities at pH 1.6 and 2.6 could not be separated, although presenting different optimal action parameters. 3. 3. The molecular weight of mytilidase, determined by gel filtration on a Sephadex G-200 column, was 36,000 ± 600.

Substratum specificity of purified peroxidase isoenzymes of horse radish root

An sieben aus Meerrettichwurzeln isolierten Isoenzymen der Peroxydase konnte substratspezifisches Verhalten nachgewiesen werden.