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L A Konoplich

Publications and source records attributed to L A Konoplich.

12 recordsLinked to original sources
PubMed1993

[ATP-dependent structural changes in chromatin].

Incubation (1 hour, 37 degrees C) of nuclei and chromatin from guinea pig spleen (but not from thymus or the liver) resulted in a proteolysis of H1 and H2A histones and accumulation of specific hydrolytic products. Sodium dodecyl sulfate gel electrophoresis revealed a decline in H1 and H2A and the appearance of new protein bands under histone H10 and between H2A and H4. ATP (10 mM) (but not cAMP or PPi) added to the incubation mixture prevented the H1 and H2A digestion and accumulation of the aforementioned products. The ATP, which protects the histones in the nucleus and chromatin from proteinases, promoted the cleavage of cytosolic low molecular weight proteins. The mechanisms of ATP-dependent chromatin structural rearrangements determining the resistance of nuclear proteins to proteolysis are discussed.

Adenosine Triphosphate↗
PubMed1991

[A rapid method of preparing the (H3-H4-H2A-H2b)(2) histone octamer in large quantities].

A simple and fast method for isolation of large amounts of the histone octamer (H2A-H2B-H3-H4)2 is proposed. This method is based on chromatin adsorption by hydroxyapatite with subsequent extraction of the histone octamer with 50 mM sodium-phosphate buffer containing 4 M NaCl pH 8.0. It was shown that the properties of the histone octamer isolated by this extractive procedure are identical with those of the histone octamer obtained by elution on a Sephadex G-100 column. The histone tetramer (H3-H4)2 and dimer (H2A-H2B) were obtained after gel filtration on Sephadex G-100 in 50 mM sodium-acetate (pH 5.6).

Animals↗
PubMed1976

[Isolation, purification and investigation of physico-chemical properties and specificity of Leu-Gly-Gly-amino peptidase].

A highly purified (237-fold) preparation of extracellular Leu-Gly-Gly aminopeptidase was isolated from the 716 strain of mould Aspergillis flavus. The enzyme was found electrophoretically and enzymatically homogeneous, using Leu-beta-naphthylimide as substrate. The pH optimum is 8.60; the temperature optimum is about 50 degrees C. The enzyme was inhibited by EDTA and completely reactivated by Co2+ ions; Ca2+ and Mn2+ ions considerably restored the enzyme activity. The enzyme showed the optimal activity during the cleavage of substrates, containing N-terminal leucine. Mild hydrolysis of leucine-free tripeptides and dipeptides with N-terminal glycine and alanine was observed. The enzyme was found to be stereospecific in some respects. Peptides with a blocked terminal NH2-group are not hydrolyzed by the enzyme.

Aminopeptidases↗
PubMedDate not supplied

[Role of metal ions in the catalytic activity of Aspergillus oryzae aminopeptidase].

The paper deals with the role of metals in the catalytic action of Asp. oryzae aminopeptidase. Cobalt ions are more specific activators than Mn2+ and Mn2+ and evoke its maximal activity. Sinergic activation of Co2+ in combination with Mn2+ and Mg2+ was not found in contrast to some aminopeptidases of animal origin. Activation of the enzyme with cobalt chloride depends on temperature. By the 10th minute of incubation the activation reaches its maximum: 650 and 900% at 20 and 40 degrees C, respectively. EDTA (10(-2) M) inactivates completely aminopeptidase for 3h; this process is intensified in the presence of leucine (10(-3) M). Aminopeptidase is also inactivated by chelating agents, such as o-phenantroline and 2,2'-dipyridyl. When the temperature rises from 20 to 40 degrees C the intensification of these reagents effect is insignificant. Cobalt ions reduce and activate to some extent the enzyme after inhibition with EDTA.

2,2'-Dipyridyl↗
PubMedDate not supplied

[Isolation and properties of enzyme preparations from the whale pancreas].

A simple and convenient technique was developed for isolation of the proteolytic enzyme complexes from the whale (Balaenoptera) pancreas. The proposed techniques enables the proteolytic complexes to be obtained with the protein yield 2.6 times higher than the classical procedure. The proteolytic activity increased 3.2 times (casein as a substrate), esterase activities, 1.4 times (N-benzoyl-L-tyrosine methyl ester as a substrate) and 1.2 times (N-alpha-benzoyl-L-arginine ethyl ester as a substrate). Soybean and barley trypsin inhibitors and ovomycoid in free and immobilized state inhibit the esterase activities of the proteolytic complexes. An additional purification of the proteolytic complexes was carried out using the affinity sorbent Soybean trypsin inhibitor--Sepharose 4B. The molecular weight of the enzymes determined by means of PAAG electrophoresis was found to be 20 000-20 500. The hydrolysis of some synthetic substrates by the proteolytic enzyme complexes obtained according to the proposed techniques was being studied.

Animals↗
PubMedDate not supplied

[Aminopeptidase system of Aspergillus flavus].

The aminopeptidases system contained in a complex of exocellular peptidhydrolases synthetized by Asp. flavus was studied. Separation of the system into individual enzymes of the type of leucin aminopeptidase, aminotripeptidase and specific leucyl-glycyl-glycine-aminopeptidase by the methods of salt fractionation. DEAE-Sephadex A-50 and DEAE-cellulose chromatography. These enzymes are characterized by a different degree of purification as well as by the presence of the multiple forms, anion and cation ones. The multiple forms differ in solubility, specific activity, chromatographic properties, thermostability. The presence of individual triglycine-aminotripeptidase is shown in the system. The differences are found in the properties of the enzymes splitting leucinamide and leucyl-glycine. There may be two different leucine aminopeptidases. Studies in correlation during hydrolysis of leucinamide and leucyl-glycyl-glycine and comparison of the fractions properties displaying the activities showed that there are no reasons to ascribe these both reactions to the effect of the same enzyme.

Aminopeptidases↗
PubMedDate not supplied

[Effect of SH-reagents and thiol compounds on aminopeptidase from Aspergillus oryzae].

It is shown that iodacetate and iodacetamide produce an insignificant inhibition of the Asp. oryzae aminopeptidase activity, para-chloromercuribenzoate is a stronger inhibitor. Dithiotreitol, beta-mercaptoethanol, reduced glutathione also cause a considerable loss in the enzyme activity. The inhibitory effect is intensified with a combined action of para-chloromercuribenzoate and EDTA. The studies of para-chloromercuribenzoate, iodacetate and iodacetamide effect on the activation of aminopeptidase apoenzyme by cobalt ions showed that the enzyme activity recovery is insignificant. It may be supposed that the enzyme thiol groups are bound with the metal ions necessary for the catalytic activity.

Aminopeptidases↗
PubMedDate not supplied

[Increase in thyroxine level in blood plasma of hypothyroid rats after administering histones].

It has been shown that the administration of total histones (H1, H3, H2B, H2A, H4), the total histones without histones H4 (H1, H3, H2B, H2A), H1 histones at concentrations of 0.001 and 1 microgram per 100 g of body weight (low and high concentrations) to intact rats during 6 days leads to the decrease of T4 amount in the blood plasm. The total histones and histone H1 at low concentration decrease the T4 amount by the coefficients 5.2 and 5.8 respectively. The corresponding coefficients for high concentration are 2.6 and 1.2. There is no difference in the action of the total histones and H1 histone at low concentration. Low concentration of histones is more effective for the decrease of T4 amount than the high one or than the antithyroid agents mercasolyl and LiCl (3 mg and 2 mM per .100 g of body weight), which decrease the amount of T4 in intact rats by the coefficient 3.6 in 38 days. Administration of histones decreases the amount of T4 in the intact rats but, on the contrary, the 3-4 fold increase is observed in hypothyroid rats, so the amount of T4 is practically reverted to the level of intact rats. The mechanism of regulation of the amount of T4 by histones is discussed.

Animals↗
PubMedDate not supplied

[Effect of adenosine triphosphate on the cleavage of H1 histones in nuclei of rat spleen and liver].

Proteolysis of histones H1b and H1(0) is observed after the incubation of rat spleen nuclei at 37 degrees C during 1 hour. Adenosine triphosphate, inorganic pyrophosphate and nicotinamide adenine dinucleotide decrease the digestion of histone H1b. ATP, PP1 and NAD+, in the case of 3 hours incubation, do not affect proteolysis of H1 histones in rat spleen nuclei. The incubation of rat liver nuclei at 37 degrees C during 1 hour leads to a decrease of the amount of histone H1b and, to much more extent, H1a. In this case ATP, PP1 and NAD+ increase proteolysis of histone H1a but practically do not affect proteolysis of H1b. After 2-hours incubations histone H1a is completely digested but histone H1b is partially preserved: ATP in this case, as well as in spleen nuclei, decreases proteolysis of histone H1b. During the 3 hours incubation, when histones H H1a and H1b are completely digested, partial digestion of histone H3 being observed, ATP does not prevent from proteolysis of histone H1b. A protein appears between the H2A and H4 histones after heating at 37 degrees C in both spleen and liver rat nuclei. Neither ATP nor PP1 and NAD+ affect the amount of this protein. It is suggested that the location of histones H1a and H1b in different chromatin domains determines the digestion of these histones by ATP-dependent proteinases.

Adenosine Triphosphate↗