[Dependence of the activity of L-amino acid oxidase in the fungus Aspergillus niger R-3 on the source of nitrogen in growth media]. / Aktivnost' oksidazy L-aminokislot u griba Aspergillus niger R-3 v zavisimosti ot istochnoka azota v srede.

Various populations of peroxisomes in cells of Aspergillus niger R-3 were formed under the growth in media containing 0.5% glucose and various sources of nitrogen (1/4 of optimal concentrations of (NH4)2SO4, L-alanine, and L-methionine). Different levels of of L-amino acid oxidase activity were found in these populations of peroxisomes.

[Changes in rat liver chromatin after administration of a mixture of amino acids]. / Izmeneniia v khromatine pecheni krys pri vvedenii smesi aminokislot.

It was shown that injections of an amino acid mixture essentially increase the number of nuclease-sensitive regions of chromatin and its active fraction (Mg2+-soluble fraction), while hydrocortisone increases the amount of the latter, which is less sensitive to the effect of DNAase II. Genome activation during nonhormonal induction after administration of the amino acid mixture or during hydrocortisone injection reflects in different ways on the parameters of melting of chromatin active fractions and on the relative content of its protein fractions.

[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.

[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.