The immobilization of the enzymeE. coli L-asparaginase on polysaccharides. III. Covalent binding with 3-bromo-2-hydroxypropyldextran

The synthesis of immobilized L-asparaginase on 3-bromo-2-hydroxypropyldextran has been effected. Some physicochemical properties of the preparations obtained have been studied. A stabilizing effect of the modification on the heat stability of the L-asparaginase has been detected. The influence of the bound polymer on the antigenic properties of the enzyme have been established.Institute of Organic Synthesis, Academy of Sciences of the Latvian SSR, Riga. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 224–228, March–April, 1981.     

Immobilization of the enzymeL-asparaginase fromE. coli on polysaccharides. VI. Preparation and properties of polymeric derivatives based on dextran carbonates

Methods have been developed for obtaining soluble and insoluble dextran carbonates. The addition of the latter to E. coli L-asparaginase has given water-soluble, gel-like, and insoluble forms of the immobilized enzyme. The influence of the bound polymer on some physicochemical properties of L-asparaginase has been determined. The antileukemic action of soluble dextran derivatives of L-asparaginase has shown that their efficiency is greater than that of the native enzyme.A. Kirkhenshtein Institute of Microbiology, Latvian Academy of Sciences, Riga. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 432–436, May–June, 1993.     

Immobilization of the enzyme L-asparaginase fromE. coli on polysaccharides. II. Covalent binding with soluble CM-cellulose

The covalent binding of L-asparaginase to soluble CM-cellulose has been carried out by the azide method, and some physicochemical properties of the preparation obtained have been studied. It has been established that the modified L-asparaginase possesses a higher heat stability than the native enzyme and also a greater resistance to proteolytic enzymes.Institute of Organic Synthesis, Academy of Sciences of the Latvian SSR, Riga. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 383–388, May–June, 1979.     

Immobilization of the enzyme E. coli L-asparaginase on a water-soluble copolymer of vinylpyrrolidone and acrolein

A method for immobilizingE. coli L-asparaginase on a copolymer of vinylpyrrolidone and acrolein has been developed and optimized. The influence on the nature of the modification of the number of acrolein residues in the copolymer has been established. The enzymatic and some physicochemical properties of the immobilized forms of the enzyme obtained have been studied.A. Kirkhenshtein Institute of Microbiology, Academy of Sciences of the Latvian SSR, Riga. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 562–565, July–August, 1988.     

L-asparaginase bound in a polyacrylamide gel

Summary The enzyme L-asparaginase fromE. coli has been included in polyacrylamide gel, and some of its properties have been investigated: stability, pH dependence, heat stability, K_m. It has been shown that the enzymegel obtained has a better stability then the native enzyme.Institute of Organic Synthesis, Academy of Sciences of the Latvian SSR, Riga. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 382–384, May–June, 1976.     

Immobilization of the enzymeL-asparaginase fromE. coli on polysaccharides. VI. Preparation and properties of polymeric derivatives based on dextran carbonates

Methods have been developed for obtaining soluble and insoluble dextran carbonates. The addition of the latter to E. coli L-asparaginase has given water-soluble, gel-like, and insoluble forms of the immobilized enzyme. The influence of the bound polymer on some physicochemical properties of L-asparaginase has been determined. The antileukemic action of soluble dextran derivatives of L-asparaginase has shown that their efficiency is greater than that of the native enzyme. A. Kirkhenshtein Institute of Microbiology, Latvian Academy of Sciences, Riga. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 432–436, May–June, 1993.     

Immobilization of the enzyme L-asparaginase from E. coli on polysaccharides I. Covalent binding with insoluble Sepharoses and CM-cellulose

Summary Immobilized L-asparaginase has been synthesized by various methods of covalent binding to insoluble Sepharoses and CM-cellulose.Some kinetic properties of the preparations obtained, the dependence of the activity on the pH of the medium, and their stability have been investigated.It has been established that the immobilized L-asparaginase possesses increased heat resistance, stability on storage, and stability to competing inhibitors.Institute of Organic Synthesis, Academy of Sciences of the Latvian SSR, Riga. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 639–643, September–October, 1976.     

Immobilization of the enzyme L-asparaginase of E. coli on polysaccharides. V. Preparation and properties of polymeric conjugates based on water-soluble CM-cellulose differing by the quantitative amounts of polymer

A precedure has been developed for the chemical binding of L-asparaginase to soluble CM-cellulose which permits final immobilization products with different degrees of modification to be obtained. Some physicochemical and immunological properties of the samples obtained have been studied.A. Kirkhenshtein Institute of Microbiology, Latvian SSR Academy of Sciences, Riga. All-Union Scientific-Research Technological Institute of Antibiotics and Enzymes for Medical Synthesis, Leningrad. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 581–587, July–August, 1987.     

Immobilization of the enzyme E. coli L-asparaginase on a water-soluble copolymer of vinylpyrrolidone and acrolein

A method for immobilizingE. coli L-asparaginase on a copolymer of vinylpyrrolidone and acrolein has been developed and optimized. The influence on the nature of the modification of the number of acrolein residues in the copolymer has been established. The enzymatic and some physicochemical properties of the immobilized forms of the enzyme obtained have been studied. A. Kirkhenshtein Institute of Microbiology, Academy of Sciences of the Latvian SSR, Riga. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 562–565, July–August, 1988.     

Reductive alkylation ofE. coli L-asparaginase

Alkylasparaginases have been obtained with the far-reaching modification of 1–10 lysine residues per subunit of the enzyme. It has been established that alkylation does not affect the stability of the enzyme, and the change in the pH optimum of the catalytic action is due to the chemical nature of the alkyl substituent.Institute of Organic Synthesis, Academy of Sciences of the Latvian SSR, Riga. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 232–235, March–April, 1980.     

Chemical modification of the tryptophan residues of the L-asparaginase of E. coli with N-bromosuccinimide

Summary The role of the tryptophan residues in the L-asparaginase molecule has been studied by the method of chemical modification with N-bromosuccinimide, and it has been established that in an acid medium this reagent modifies all four tryptophan residues present in the molecule, completely suppressing the activity of the enzyme.The substrate — L-asparagine — and a competing inhibitor — S-benzyl-N-benzyloxycarbonyl-L-cysteine — protect the L-asparaginase from the action of N-bromosuccinimide, which shows the role of the tryptophan in the catalytic center of the L-asparaginase.Institute of Organic Synthesis, Academy of Sciences of the Latvian SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 228–231, March–April, 1975.     

Immobilization of the protease ofBacillus mesentericus on Silochromes

The immobilization of the protease ofBacillus mesentericus on Silochrome using cyanuryl chloride, 2,4-toluylene diisocyanate, glutaraldehyde, thionyl chloride, phosphorus tribromide, titanium tetrachloride, and zirconium and hafnium oxychlorides as cross-linking reagents has been studied. The greatest binding and retention of activity were observed with the use of transition-metal salts. A comparison of the properties of the native and immobilized preparations has been made. The stability of the immobilized protease on storage and repeated use has been investigated.Physicochemical Institute, Academy of Sciences of the Ukrainian SSR, Odessa. Institute of Microbiology Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 104–109, January–February, 1980.     

Immobilization of a protease on grafted polyethylenes

It has been shown that when the protease ofBacillus mesentericus is immobilized on polyethylene with grafted-on polyacrylic acid by the carbodiimide method there is a considerable retention of its activity and an increase in its thermal stability, and the immobilized preparations are active on repeated use.Institute of Physical Chemistry, Academy of Sciences of the Ukrainian SSR, Odessa. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 512–516, July–August, 1983.     

X-ray structural investigation of alkaloids. II. Molecular structure and absolute configuration of (?)-pseudokopsinine

Summary By a complete x-ray structural investigation, the structural formula of (–)-pseudokopsinine has been refined and its absolute configuration has been determined.Institute of Heteroorganic Compounds, Academy of Sciences of the USSR, Moscow. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 197–206, March–April, 1976.     

Some kinetic features of the hydrolysis of L-asparagine withE. coli asparaginase

The influence of various effectors (methanol, neutral salts) on the kinetic parameters K_M and k_cat has been studied. The hypothesis has been expressed that chloride ions are responsible for the worsening of the binding of the substrate to the enzyme. The temperature dependence of the kinetic parameters K_M and k_cat for the enzymatic hydrolysis of L-asparagine has been obtained. It has been shown that the graph of log k_cat versus 1/T has a break at 30°C. The effective activation energies below and above the critical point are 6.5 and 3.6 kcal/mole, respectively.Institute of Organic Synthesis, Academy of Sciences of the Latvian SSR, Riga. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 707–709, September–October, 1979.     

Immunochemical characterization of a proteolytic enzyme — Protease A from cotton seeds

It has been established by double immunodiffusion in agar that protease A (a proteolytic enzyme from dormant cotton seeds hydrolyzing the native reserve proteins) is present for the first 3–4 days during the germination of the seeds. An immunological affinity between trypsin and protease A has been revealed which indicates the presence of common structural elements in them.Institute of Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 109–110, January–February, 1991.     

Alanto- and isoalantolactones

Literature information (up to 1989) on two typical representatives of the eudesmane series of sesquiterpene lactones — alanto- and isoalantolactones — has been generalized for the first time. Questions of their occurrence in nature, their ecological role, isolation, and synthesis, and also their chemical and biological properties, are considered. The possibility has been shown of passing by a series of successive chemical transformations to other naturai sesquiterpene lactones with the same or a different type of skeieton.Institute of Organic Synthesis, Latvian SSR Academy of Sciences, Riga. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 307–320, May–June, 1990.     

Isolation and antibiotic properties of cis-hexadeca-4,7,10,13-tetraenoic acid from the algaScenedesmus obliquus UA-2-6

Summary By the method of checking antibiotic activity, conditions have been selected for the isolation of cis-hexadeca-4,7,10,13-tetraenoic acid from the fatty-acid fractions of the lipids ofScenedesmus obliquus UA-2-6. Its structure has been confirmed and it has been established that this acid possesses a broad spectrum of antibiotic action.Institute of Microbiology, Academy of Sciences of the Uzbek SSR, Tashkent. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 379–385, May–June, 1978.     

Preparation of adsorbed lipase and its properties

Summary 1. Under certain conditions, lipase immobilized on cellulose-based ion-exchange materials can be obtained. The best adsorbent is DEAE-cellulose.2. The optimum conditions for the immobilization of lipase on DEAE-cellulose are pH 8.0, time of contact with the support 15–20 min, temperature 10° C.3. The immobilized lipase (DEAE-cellulose-lipase) retains the main functional properties of the native enzyme.Department of Microbiology, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 267–271, March–April, 1977.     

X-ray structural investigation of alkaloids. III. Molecular structure and absolute configuration of (+)-excelsine

Summary On the basis of a complete x-ray structural investigation, the structural formula of (+)-excelsine has been refined and its absolute configuration has been determined.Institute of Heteroorganic Compounds, Academy of Sciences of the USSR, Moscow. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 206–217, March–April, 1976.