[GTP-dependent dopamine reception in central nervous system tissues in the pond snail]. / GTF-zavisimaia retseptsiia dofamina v tkaniiakh tsentral'noi nervnoi sistemy bol'shogo prudovika.

Guanosine-5'-triphosphate (GTP)-dependent binding of the agonist D1 dopamine (DA) receptor ligand [H3]-SKF 38393 is described. It is shown that binding of [H3]-SKF 38393 with two different populations takes place in the presence of guanylyl nucleotides, when they are absent--with one population. It is demonstrated using GDP-alpha-P33 binding analysis that the GDP in equilibrium with GTP exchange rate gets higher as a result of activation of DA receptors in the membrane from the mollusc nervous tissues. Influence of the catalytic subunit of the protein kinase A (cPKA) on the [H3]-SKF 38393 and GDP-alpha-P33 is investigated. Obvious influence of the cPKA on [H3]-SKF 38393 binding is not observed, while basal and DA-induced GDP in equilibrium with GTP exchange in membranes of the mollusc nervous tissues is considerably inhibited.

[Dopamine effect on ionic conduction and adenyl cyclase activity in the central nervous system of the pond snail]. / Vliianie dopamina na ionnuiu provodimost' i aktivnost' adenilattsiklazy v tsentral'noi nervnoi sisteme prudovika.

The mode of dopamine action (DA) was investigated both on identified neurons (growth hormone producing cells--GHC) and on the membrane fraction of the CNS tissue homogenate. Adenylate cyclase activity (ACA) in the Lymnaea membrane depended on the GTP, stimulated and inhibited by different well known mediators, dopamine action being one of them. DA produced a stimulatory and inhibitory action on ACA. Direction of the DA action depended on the GTP concentration: at lower concentration of the GTP DA was a stimulator of ACA, at higher--an inhibitor. It is shown that inhibitory influence of DA on ACA was prevented by treatment of the membrane of the catalytic subunit of the protein kinase A (cPKA). It is particularly noticeable that inhibitory influence of cPKA-dependent phosphorylation reduced the inhibitory action of ALF4-, a G-protein activator. Effect of DA application on the GHC induced appearance of inward and outward currents through the neuronal membrane.

[Influence of phosphorylation on the functional properties of the sodium channel reconstructed in an artificial membrane]. / Vliianie fosforilirovaniia na funktsional'nye svoistva natrievogo kanala, rekonstruirovannogo v iskusstvennuiu membranu.

Phosphorylation of the reconstructed TTX-sensitive cytosolic protein of the bovine brain has been studied. Some properties of the protein are similar to those of the membrane potential-dependent sodium channel. It is shown that the influence of phosphorylation by protein kinase A on the reconstructed channel greatly depends on the mode of reconstruction. Phosphorylation fo reconstructed channels in the open state leads to their closing. Preliminary phosphorylation of channel-forming protein results in a considerable increase of the activation effect of veratrine and scorpion toxin.

[Effect of a catalytic subunit of cAMP-dependent protein kinase on acetylcholine-induced chloride currents in mollusk neurons]. / Vliianie kataliticheskoi sub"edinitsy tsAMP-zavisimoi proteinkinazy na atsetilkholinindutsiruemye khlornye tochki v neironakh molliuska.

It is shown that the amplitude of ACh-induced chloride currents decreases with introduction of cAMP in dialyzed neurons of Helix pomatia, the rate of desensitization of the acetylcholine receptors (AChR) being insignificantly changed. Introduction of an active catalytic subunit (c.s.) of cAMP-dependent protein kinase (cAMP-PK) mimics this effect. It is supposed that the influence of cAMP on the functional properties of the AChR is mediated by the activation of cAMP-PK and further phosphorylation of the AChR by the catalytic subunits of this protein kinase.

[Polyamine modulation of phosphorylation of channel-forming cytosolic protein in bovine brain]. / Modulirovanie poliaminami fosforilirovaniia kanalformernogo tsitozol'nogo belka mozga byka.

Phosphorylation of the bovine brain TTX-sensitive cytosolic protein which is similar in several functional properties to the membrane potential-dependent sodium channel has been studied. The results obtained indicate that the cytosolic protein is a substrate for cAMP-dependent phosphorylation. Polyamines at a concentration of 5.0 mmol/l inhibit markedly phosphorylation of the cytosolic protein. Spermine is shown to be the most effective inhibitor. It is suggested that polyamines may modulate the cell sodium channel function.

[Endocrine intestinal low molecular weight factor inhibits Na+,K+- ATPase activity of enterocytes]. / Endokrinnyi intestinal'nyi nizkomolekuliarnyi faktor ingibiruet Na+,K+-ATP-aznuiu aktivnost' énterotsitov.

The biological activity of the endocrine secretum fraction isolated from the rat duodenum is determined. The fraction with the molecular weight about 3 kDa is found to possess the factor which inhibits the Na+,K+-ATPase activity of enterocytes. It is found that the inhibitory factor secretum depends on the solution which irrigates the duodenum cavity. The possible regulatory role of the intestine inhibitory factor is under discussion.

[Digestive and transport enzymes of the small intestine under the action of low-mineralized water "Naftusya" and its components]. / Pishchevaritel'nye i transportnye fermenty tonkoi kishki pod deistviem malomineralizovannoi vody "Naftusia".

Mineral water Naftusya and its components: macrosalt analog and bitumen fraction have been studied in vitro for their effect on enzymes of the mucous small intestine membrane: M2+ and Na+, K+-ATPase, alpha-amylase, proteinase and leucine aminopeptidase. It is shown that certain components of mineral water are able to change activity of some enzymes. Transport Na+, K+-ATPase proved to be the most sensitive to the action of studied factors. Mineral water and bitumen fraction induced an increase of the enzyme activity by 23, 20 and 45%, respectively. Mineral water and its salt analog induced inhibition of leucine aminopeptidase: its activity decreased by 16 and 15%, respectively. Digestive enzymes: alpha-amylase and proteinase are resistant to the action of mineral water and its components.

Kinetic characteristics of fibrinogen and fibrin hydrolysis by plasmin 1 and 2 and miniplasmin.

Fibrinogen and fibrin hydrolysis by native plasmin 1 and 2 and by miniplasmin was studied. The degree of hydrolysis was estimated by the number of amino groups determined with trinitrobenzene sulphonic acid. The process was shown to obey Michaelis-Menten kinetics. Kinetic parameters of fibrinogen and fibrin hydrolysis by plasmin forms 1 and 2 were identical (KM = 6.5 X 10(-6) M, kcat = 7.1 sec-1) while for hydrolysis by miniplasmin KM = 20.0 X 10(-6) M, kcat = 3.58 sec-1. Thus, it was demonstrated that enzymatic properties of plasmin are to some extent dependent on the presence of lysine-binding sites. However, this appears not to have a decisive effect on fibrinolytic process.

[Comparative evaluation of fibrinogen and fibrin hydrolysis with plasmin]. / Sravnitel'noe izuchenie gidroliza fibrinogena i fibrina plazminom.

A high-sensitive method is developed for determining the degree of plasmin-catalyzed fibrinogen hydrolysis by the released amino groups stained with trinitrobenzene sulphoacid. The method permits determining 0.02-0.08 casein units of plasmin. The method made it possible to establish that after streptokinase activation plasmin hydrolyzes equally fibrinogen and fibrin in solution and as gel. When a tissue activator is used, fibrin intensifies significantly the plasminogen activation. Inhibition of plasmin by an inhibitor produced from soya is considerably slowed down in fibrin gel.

[Micromethod for plasminogen determination]. / Mikrometod opredeleniia plazminogena.

Conditions are developed for determining potential activity of plasminogen in amine groups formed in casein hydrolysis. Two variants of determination are suggested: by means of a ninhydrin reagent and trinitrobenzene sulphoacid. The method permits determining 0.02-0.1 of plasmin casein units (cas. units); it is 20 times as sensitive as the known caseinolytic method based on determination of the degree of tyrosine absorption.

[Properties of Streptomyces griseus aminopeptidase]. / Izuchenie svoistv aminoptndezy/L/C streptomyces griseus.

The paper deals with studying the properties of aminopeptidase isolated from Str. griseus culture fluid. The preparation is characterized by a high specific activity and heat stability, it has no admixtures of carboxypeptidases and proteinases. The enzyme is easily inhibited by EDTA, but the addition of Ca2+ evokes its complete reactivation. A partial recovery of the activity may be also reached under the influence of some other bivalent metals. In hydrolysis of di- and tripeptides it is shown that the enzyme has a preferential effect on the substrates with N-terminal leucine. Peptides with N-terminal alanine, valine and glycine are almost not hydrolyzed. The use of the native insulin and decapeptide with the known amino acidic sequence as substrates shows that aminopeptidase can hydrolyze proteins and peptides with the successive release of some amino acids: phenylalanine, serine triptophane, valine, asparagine, etc. Glycine is difficult for removal and may inhibit the further hydrolysis of the polypeptide chain.

[Study of bone tissue insoluble collagen hydrolysis by Streptomyces griseus protease using the method of N-terminal analysis]. / Doslidzhennia metodom N-kintsevogo analizu gidrolizu nerozchinnogo kolagenu tkanini kistok proteazoiu Streptomyces griseus.

Str. griseus protease hydrolyzes essentially insoluble collagen of bone tissue, with 34.5% of protein solubilized and 6.0% of peptide bonds splitted. 60.0 M of N-terminal amino acids is formed per 10(5) g of protein, out of them 16.8 in the fraction of free amino acids, 32.3 M in the fraction of soluble DNP-peptides and 10.9 M in that of insoluble DNP-peptides. Under the effect of trypsin the amount of collagen changing to the soluble form is thrice as low and the splitted peptide bonds are ten times as low as in case of the Str. griseus protease action. The peptide bonds incorporating the N-end of serine, threonine, glycine are more available for protease. It is supposed that under used conditions Str. griseus protease hydrolyzes not only telepeptides but also the main molecule of collagen.

[Study of gelatin hydrolysis by Streptomyces griseus protease using the method of N-terminal analysis]. / Dsolidzhennia metodom N-kinstevoho analizu hidrolizu zhelatynu proteazoiu Streptomyces griseus

The ariticle deals with gelatin hydrolysis by the crystalline preparation of the Str. griseus protease. 12.1% of 1080 peptide bonds available in 105 g of protein split for 24 h at 40 C. The bonds of 8-9 types which involve N-end of glycine, serine, phenylalanine, threonine, leucine, valine, glutaminic acid, lysine break at once. The process occurs with delay, and 0.25, 0.5, 6 and 24 h after there occurs a breakage of the 42d, 61st, 117th and131st bonds. The middle size of the peptide chain of the initial protein is 604 amino acid residues, in the hydrolyzate 30, 22, 11.6 and 11.3 residues are found within these intervals, respectively. Main changes occur in the fraction of soluble peptides where number of N-terminal amino acids rises from 25 to 80. Some data are obtained on the total specificity of the Str. griseus protease. It splits mostly the bonds which involve the N-end of glycine (51%), alanine 2%), serine (9%). The content of the definite amino acid in gelatin shows that hydrolysis bonds of serine and threonine accounts for 35.2 and 35.6%, valine and leucine for 23.6 and 24.7%, glycine and alanine for 18.8 and 13%, methionine, lysine, glutaminic and asparagic acids for 7-9%; the proline bonds are not splitted at all. An assumption is advanced on the presence of four groups of bonds in gelatin; the rate of their hydrolysis corresponding to the enzyme specificity. The Str. griseus protease splits as free amino acids 10 mol of serine of 35,5, 5.5 mol of leucine of 26.3, 3.6 mol of threonine of 19.8 and only 4 mol of glycine of 363 available in gelatin.

[Isolation and several properties of Streptomyces griseus carboxypeptidase]. / Vydelenie i nekotorye svoistva karboksipeptidazy Streptomyces griseus

Enzymatic and physico-chemical properties of homogenous preparation of carboxypeptidase from Streptomyces griseus are studied. pH-Optimum is found to be 7.9 and 8.2 under the hydrolysis of cbs-Gly-Leu and hyppuryl-arg respectively, temperature optimum --60 degrees C. The enzyme splits more efficiently basic amino acids and leucine from N-terminal-protected dipeptides. Str. griseus carboxypeptidase is activated by reducting agents (NaCN, cisteine, ascorbic acid), it is inhibited by KMnO4 and it does not belong to "serine" type enzymes. SH-groups are essential for the enzyme activity. No significant effect of metal ions on the enzyme activity is observed. The inhibitory effect of EDTA developed only after the prolonged treatment. The enzyme has one N-terminal group (alanine), which evidences the presence of one polypeptide chain in the enzyme molecule.