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I V Malofeeva

Publications and source records attributed to I V Malofeeva.

9 recordsLinked to original sources
PubMed1979

[Kinetics of the aspartate-aminotransferase reaction catalyzed by free and immobilized cells of E. coli].

The kinetics of the aspartate-aminotransferase reaction were studied, using free and immobilized cells of E. coli, strain 85 as an enzyme source. It was shown that the reaction is limited by mass transport of the reagents through the bacterial cell membrane even at high concentrations of the substrates in the surrounding solution. The polyacrylamide gel-incorporated cells of E. coli, strain 85 catalyze the aspartate-aminotransferase reaction more effectively as compared to free or destroyed cells. In the latter case the reaction is characterized by the following kinetic parameters: the effective values of the stationary rate of the product accumulation and its stationary efflux from the cell are equal to (15,37 +/- 0.4) . 10(-6) mole/s/mg of protein and (3,01 +/- 0,8) . 10(-20) mole/s per 1 cell. respectively. The steady-state constant for glutamate synthesis from aspartic acid is equal to 0,22--0,23.

Aspartate Aminotransferases↗
PubMedDate not supplied

[Utilization of nitrogen compounds by phototrophic bacteria].

Phototrophic purple and green bacteria differ by their ability to assimilate nitrogen compounds. Thiocapsa roseopersicina utilizes not only ammonium and nitrates, as a source of nitrogen, but also urea, azoguanine, cytosine and some amino acids. The non-sulphur bacterium Rhodopseudomonas palustris grows at the account of amine nitrogen of a larger number of amino acids than the sulphur bacterium. Chlorobium limicola 1. thiosulfatophilum grows only on media containing urea and methylamines. Formation of amino acids by the studied phototrophic bacterial cultures is related to amination of alpha-ketoglutarate. Purple bacteria possess also the activity of aspartate dehydrogenase.

Amino Acids↗
PubMedDate not supplied

[Use of urea by purple bacteria].

Strains of purple sulfur bacteria (Chromatium minutissimum, Ectothiorhodospira shaposhnikovii, Thiocapsa roseopersicina, Lamprobacter modestohalophilus) and nonsulfur bacteria (Rhodopseudomonas palustris, Rh. spheroides, Rhodospirillum rubrum) grow in media containing urea as a source of nitrogen at concentrations from 0.5 to 5.0%. They can also utilize the carbon of urea and thus grow in the absence of bicarbonate. Urea is decomposed by all the studied purple bacteria with the participation of urease. In a number of strains, the enzyme is inducible and is synthesized only in the presence of urea. However, it is constitutive in certain purple bacteria (L. modestohalophilus, Rh. palustris, Rh. spheroides). The strains of purple bacteria differ in the activity of urease and in its susceptibility to ammonium ions.

Chromatiaceae↗
PubMedDate not supplied

[Synthesis of L-aspartic acid by Escherichia coli and Pseudomonas fluorescens as related to the cultivation conditions].

The capacity of the cultures Escherichia coli str. 85, 113, BC, C and K-12 and Pseudomonas fluorescens str. 1 to synthesize L-aspartic acid from fumarate and ammonium ions was studied. E. coli str. 85 was shown to synthesize the largest amounts of aspartic acid. The cultivation conditions which helped to increase the activity several times were selected. The product of fumarate amination by ammonium ions was identified and found to be L-isomer of aspartic acid with an angle of rotation of [alpha] 20/D = +25,5 degrees in 6 N HCl.

Aspartic Acid↗
PubMedDate not supplied

[Aspartate aminotransferase activity of different strains of Escherichia coli].

Aspartate-aminotransferase activity was measured in strains of Escherichia coli grown no meat infusion broth. As an enzyme cells with damaged permeability of the cytoplasmatic membrane were used. The cells were damaged by an addition of toluene at a concentration of 1% of the reaction mixture by volume. These cells showed 50--60% aspartate-aminotransferase activity as compared with aliquotes of the cell-free extract. E. coli synthesized oxalacetic and glutamic acids from L-aspartic acid and alpha-ketoglutaric acid. Glutamic acid was identified by thin-layer chromatography on Fixion plates. E. coli str. 85 cells and their extracts grown on the synthetic medium containing glucose or glycerol showed a two-fold specific aspartate-aminotransferase activity as compared with those cultivated on meat-infusion broth.

Aspartate Aminotransferases↗
PubMedDate not supplied

[L-asparatic acid synthesis from ammonium fumarate by free and immobilized Escherichia coli cells].

E. coli 85 cells with a high aspartate-ammonia-lyase activity were immobilized through polyacrylamide gel incorporation. Proper conditions to assay aspartase activity of E. coli cells were developed. Kinetic patterns of aspartate-ammonia-lyase reaction catalyzed by free and immobilized E. coli 85 cells were studied. The synthesis of L-aspartic acid from ammonium fumarate had the following characteristics: specific activity of (4--6) . 10(-5) mmole/mg.sec for free cells and (6--8) . 10(-5) mmole/mg.sec for immobilized cells with their content in polyacrylamide gel of 5--10 mg protein per g wet gelm pH 8.3--10.0.

Aspartic Acid↗