[Comparative study of the activity of arginase isoenzymes in brain tumors of humans and experimental animals]. / Sravnitel'noe izuchenie aktivnosti izoform arginazy opukholei golovnogo mozga cheloveka i éksperimental'nykh zhivotnykh.

Isoenzyme spectrum and total activity of arginase were studied in rat brain during growth of transplanted neurinoma and glioma as well as in malignant tissues of human brain. After transplantation of the tumors two peaks of arginase activation were observed within 2-4 days in rat brain tissues and within 16 days in tumoral tissue. Positively charged isoenzyme I of arginase was mainly activated but activity of neutral isoenzyme II was unaltered or slightly decreased. In human brain tumors activity of isoenzyme I was also prevailed, while activity of isoenzyme II was increased in some cases. Regulation of the arginase activity appears to occur by a complex mechanism and the enzyme plays a key role in development of nervous tissue neoplasms.

[Brain arginase isoenzyme activity during the growth of neurinomas]. / Aktivnost' izoform arginazy mozga v period rosta nevrinomy.

Activity of arginase and of its isoenzymes was studied in rat brain tissue and in neurinoma tissue (strain 10-13-3) at the period of growth of the tumor in trigeminal nerve. Within the fourth day after the tumor transplantation the total activity of arginase was increased in brain and distinct alterations were found in the isoenzyme spectrum, mainly in the impaired hemisphere. The enzymatic activity was increased in the tumoral tissue within 16 days; the activation was localized in the malignant tissue and did not extent into surrounding nerves. In all the samples studied the positively charged isoenzyme I was activated, whereas the activity of the isoenzyme II was altered only slightly and usually tended to decrease. It was the activity of the isoenzyme I, which appeared to be altered in the growing tumor.

[Changes in arginase activity during neurinoma growth]. / Izmenenie aktivnosti arginazy v protsesse rosta nevrinomy.

Arginase activity was studied in the brain and other tissues of the rat at the different periods of neurinoma growth. The activity of the enzyme was considerably activated in the affected hemisphere on the 4th day, in the skin of the head and thigh on the 6th day after tumor transplantation. Elevation in arginase activity in the neoplasm itself was recorded on the 16th day. The data obtained point to the physiological significance of arginase during neurinoma growth.

[Comparative study of the action of O-phenanthroline metal complexes and a number of other compounds on the activity of brain arginase isoforms]. / Sravnitel'noe izuchenie deistviia O-fenantrolinovykh metallokompleksov i riada drugikh soedinenii na aktivnost' izoform arginazy mozga.

Two isoforms of arginase were isolated from rat brain tissue: isoform I-adsorbed on CM-Sephadex and isoform II-unadsorbed on the sorbent. In samples with arginine as a substrate Km values for isoforms I and II constituted 1.7 X 10(-3) M and 3.8 X 10(-3) M, respectively. EDTA and o-phenanthroline inhibited these both brain arginase isoforms. As shown in experiments with o-phenanthroline metal complex affecting the brain arginase activity some copper complexes were able to inhibit most effectively the activity of the isoform II. Activity of both these isoforms was inhibited also by dithiothreitol, proline and acetaldehyde. Complexes of o-phenanthroline with Co2+ and Fe2+ inhibited only slightly the activity of the isoform II and did not affect the isoform I. These data showed that brain arginase isoforms were markedly distinct in their properties from the ureotelic liver tissue arginase.

[Effect of alcohol intoxication on activity of enzymes in ethanol oxidation and on arginase activity in rat liver]. / Vliianie alkogol'noi intoksikatsii na aktivnost' fermentov okisleniia étanola i arginazy pecheni krys.

In chronic alcohol intoxication activity of alcohol-oxidizing systems in liver tissue was not distinctly altered as shown by estimation of alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (AcDH) activities, whereas the arginase activity was increased 1.5-2-fold. At the same time, the activities ADH, AcDH and arginase tended to decrease in acute alcohol intoxication of slight and middle degree. These alterations in the enzymatic activity were more pronounced in acute intoxication occurring simultaneously with chronic alcoholization. Lethal doses of alcohol caused a decrease in ADH and AcDH activities but did not affect the arginase activity.

[Arginase activity in various tissues of rats in alcohol intoxication]. / Aktivnost' arginazy razlichnykh tkanei krysy pri alkogol'noi intoksikatsii.

Effects of acute and chronic alcohol intoxication on activities of arginase, alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (AcDH) were studied in rat liver, brain and kidney tissues. Alcohol intoxication altered both ureotelic (liver) and non-ureothelic (brain, kidney) arginase activity. The arginase activity in all the tissues studied was increased in chronic alcohol intoxication. Elevation in the arginase activity in liver tissue indicates that the urea cycle is activated as well as that hyperproduction of glutamic acid in brain may occur. Specific inhibitory effects of ethanol and acetaldehyde might be responsible for alterations of the arginase activity in all the tissues studied in acute alcohol intoxication. In vitro acetaldehyde at 5 X 10(-6) M concentration inhibited the arginase activity in partially purified preparations of brain and kidney tissues by 40-50% and of liver tissue--by 10-15%; 10% ethanol inhibited the liver enzyme by 90% and affected only slightly the activity of brain arginase.

[Multiple forms of rat liver arginase]. / Mnozhestvennye formy arginazy pecheni krysy.

Two differently charged isoforms of arginase were isolated from rat liver and partially purified. The isoelectric point for isoform I possessing more than 90% of the total arginase activity lies around 9.3, while that for isoform II lies around pH 7.0. Both isoforms have similar molecular weights (120,000) and close Km values (1-3 mM). In order to stabilize the enzyme activity both isoforms were obtained in an immobilized state. Study of the effects of some cholate compounds, SH-reagents and inhibitors on soluble and immobilized isoforms revealed some differences in the properties of these isoforms. Isoform II subunits are more tightly bound to Mn2+ than those of isoform I; the role of SH-groups in manifestation of the catalytic activity of the isoforms appears to be different. Isoform I possessing a positive charge (this is in agreement with the literary data) can be related to ureothelic enzymes, while isoform II is close to non-ureothelic arginases from brain and kidney not coupled with the ammonium detoxication mechanism.

[Binding of (125I)-tyrosyl-bradykinin to subcellular vascular fractions]. / Sviazyvanie (125I)tirozil-bradikinina s subkletochnymi fraktsiiami Sosudov.

The binding of the biologically active bradikinin analog--[125I]-tyr-B to partially purified fractions of plasma membranes from rat and rabbit aorta and from human umbilical veins and arteries has been studied. It was shown that some regions of vascular plasma membranes have a high affinity for the analog (Kac = 2--6.10(8) M-1). The capacity for competitive substitution of angiotensin II and [125I]-angiotensin II-tyr-B for [125I]-tyr-B suggests the similarity of the binding sites of plasma membranes of the two biologically active peptides--bradikinin and angiotensin II.

[Interaction of immobilized carboxypeptidase with a natural inhibitor from human blood plasma]. / Vzaimodeistvie immobilizovannoi karboksipeptidazy s prirodnym ingibitorom iz plazmy krovi cheloveka.

Carboxypeptidase N was bound covalently to CNBr-activated Sepharose 4B without decrease in the enzymatic activity. Interaction of the immobilized enzyme with native low molecular inhibitor from human blood plasma was accompanied by formation of the stable Co2+-dependent complex, which is partially dissociated in presence of 2 M NaCl. The data obtained suggest that the inhibitor studied possesses the specific effect on the carboxypeptidase N activity.

[Isolation, purification and properties of a carboxypeptidase inhibitor from human blood serum]. / Vydelenie, ochistka i svoistva ingibitora karboksipeptidazy i iz syvorotki krovi cheloveka

Partially purified low molecular component, which inhibited the carboxypeptidase N activity in samples with hippuryl-L-lysine and bradikinine as substrates, was isolated from human blood serum by means of chromatography on DEAE-Sephadex, ultrafiltration of the fractions obtained through Amicon membranes UM-10 or UM-2 and subsequent gel filtration through Sephadex G-10. The probable molecular weight of the inhibitor was 2000. The inhibitor was thermolabile; its inhibitory activity was decreased by 50% after 30 min boiling in 0.01 M phosphate buffer, pH 7.8. Trypsin and chymotrypsin did not influence the inhibitory properties of the factor. Hydrolysis of the low molecular component in 6 N HCl at 110 degrees C within 18 hrs and subsequent studies of the amino acid composition showed a number of amino acids in the hydrolysate; the hydrolysate exhibited the inhibitor activity of the initial substance.