OCCURRENCE AND PROPERTIES OF L-AMINOACID:2-GLYOXYLATE AMINOTRANSFERASE IN PLANTS

1965 ◽  
Vol 43 (4) ◽  
pp. 495-506 ◽  
Author(s):  
E. A. Cossins ◽  
S. K. Sinha
Keyword(s):  
Enzyme System ◽  
Intracellular Localization ◽  
Plant Tissues ◽  
Amino Group ◽  
Transaminase Activity ◽  
Higher Plant ◽  
Amino Donor ◽  
Glyoxylate Aminotransferase

Extracts prepared from a variety of higher plant tissues have been examined for L-aminoacid:2-glyoxylate aminotransferase (glyoxylate transaminase) activity. This enzyme has been detected in extracts prepared from sunflower cotyledons, corn coleoptiles, mature pea leaves, and carrot storage tissues.Measurement of glyoxylate transaminase activity was based on ability of the extracts to convert glyoxylate- 1,2-C14 to glycine-1,2-C14 in the presence of a suitable amino group donor.Properties of this enzyme system, including amino donor requirements, inhibition, pH optima, and reversibility, have been studied using extracts prepared from mature pea leaves. In sunflower cotyledons, glyoxylate transaminase activity decreased during germination. Studies of the intracellular localization of this enzyme have shown that glyoxylate transamination occurs mainly in the cytoplasm.

scholarly journals Screening and Comparative Characterization of Microorganisms from Iranian Soil Samples Showing ω-Transaminase Activity toward a Plethora of Substrates

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 874 ◽  
Author(s):  
Najme Gord Noshahri ◽  
Jamshid Fooladi ◽  
Christoph Syldatk ◽  
Ulrike Engel ◽  
Majid M. Heravi ◽  
...  
Keyword(s):  
Soil Microorganisms ◽  
Solvent Tolerance ◽  
Chiral Amines ◽  
Optimal Conditions ◽  
Transaminase Activity ◽  
Rdna Sequencing ◽  
High Enzyme ◽  
Amino Donor ◽  
Selection Of

In this study, soil microorganisms from Iran were screened for ω-transaminase (ω-TA) activity based on growth on minimal media containing (rac)-α-methylbenzylamine (rac-α-MBA) as a sole nitrogen source. Then, for the selection of strains with high enzyme activity, a colorimetric o-xylylendiamine assay was conducted. The most promising strains were identified by 16S rDNA sequencing. Five microorganisms showing high ω-TA activity were subjected to determine optimal conditions for ω-TA activity, including pH, temperature, co-solvent, and the specificity of the ω-TA toward different amine donors and acceptors. Among the five screened microorganisms, Bacillus halotolerans turned out to be the most promising strain: Its cell-free extract showed a highly versatile amino donor spectrum toward aliphatic, aromatic chiral amines and a broad range of pH activity. Transaminase activity also exhibited excellent solvent tolerance, with maximum turnover in the presence of 30% (v/v) DMSO.

Adenylate Kinase from Maize Leaves: True Substrates, Inhibition by P1 , P5-di(adenosine-5′) pentaphosphate and Kinetic Mechanism

1990 ◽  
Vol 45 (6) ◽  
pp. 607-613 ◽  
Author(s):  
Leszek A. Kleczkowski ◽  
Douglas D. Randall ◽  
Warren L. Zahler
Keyword(s):  
Adenylate Kinase ◽  
Kinetic Studies ◽  
Kinetic Mechanism ◽  
Reverse Reaction ◽  
Plant Tissues ◽  
Forward Reaction ◽  
Higher Plant ◽  
Maize Leaves ◽  
Variable Substrate ◽  
Free Magnesium

Abstract Purified maize leaf adenylate kinase (AK) was shown to use one molecule each of free ADP and Mg-ADP as well as free AM P and Mg-ATP as substrates in the forward and reverse reaction, respectively. This was deduced from substrate kinetic studies which were carried out under conditions of strictly defined concentrations of free and Mg-complexed adenylate species and under controlled free magnesium levels. Apparent Km values of the substrates of AK were 3 and 6 μM for ADP and Mg-ADP, respectively (forward reaction), and 69 and 25 μM for free AMP and Mg-ATP, respectively (reverse reaction). The enzyme was competitively inhibited by P1,P5-di(adenosine-5′)pentaphosphate (Ap5A), a bisubstrate analog of AK reaction, with apparent Ki values in the range of 11 -80 nM , depending on variable substrate. Substrate kinetic studies and inhibition patterns with Ap5A suggested a sequential random kinetic mechanism in both directions of the reaction. These properties of a higher plant AK are similar or analogous to those previously established for the enzyme from yeast and non-plant tissues.

The Synthesis of Cellulose by an Enzyme System from a Higher Plant

1964 ◽  
Vol 86 (2) ◽  
pp. 309-310 ◽  
Author(s):  
A. D. Elbein ◽  
G. A. Barber ◽  
W. Z. Hassid
Keyword(s):  
Enzyme System ◽  
Higher Plant

A reliable method for the estimation of DNA in higher plant tissues

1976 ◽  
Vol 71 (1) ◽  
pp. 308-312 ◽  
Author(s):  
J. Singh ◽  
D. Siminovitch
Keyword(s):  
Reliable Method ◽  
Plant Tissues ◽  
Higher Plant

ADAPTATION OF THE CARBON DIOXIDE YIELD IN THE NINHYDRIN REACTION TO THE STUDY OF TRANSAMINATION IN PLANT TISSUES

1956 ◽  
Vol 34 (1) ◽  
pp. 15-24
Author(s):  
F. S. Cook
Keyword(s):  
Carbon Dioxide ◽  
Simple Technique ◽  
Enzyme Concentration ◽  
Plant Tissues ◽  
Similar Reaction ◽  
Transaminase Activity ◽  
Enzyme Preparations ◽  
Optimum Ph ◽  
Ninhydrin Reaction ◽  
Chloramine T

A simple technique for assaying the glutamic–aspartic transaminase activity in plant tissues making use of titrimetric measurements of the carbon dioxide yield in the ninhydrin reaction with alpha-amino acids is described. The necessary apparatus is simple and inexpensive. The success of this method is verified by comparing results with those obtained on the same or similar reaction mixtures by quantitative paper chromatography, and by the chloramine-T method. Kinetic data on enzyme preparations of corn radicle homogenates and radicle segments frozen intact have been successfully obtained. The glutamic–aspartic transaminase is very active in corn radicles, giving high initial velocities. Per cent transamination per 10 min. period varies linearly with enzyme concentration. The optimum pH for the homogenates is at 8.5.

scholarly journals THE INTRACELLULAR LOCALIZATION OF INORGANIC CATIONS WITH POTASSIUM PYROANTIMONATE

1970 ◽  
Vol 45 (2) ◽  
pp. 355-366 ◽  
Author(s):  
Carlos J. Tandler ◽  
César M. Libanati ◽  
Carlos A. Sanchis
Keyword(s):  
Cell Morphology ◽  
Intact Cell ◽  
Intracellular Localization ◽  
Bound State ◽  
Plant Tissues ◽  
Inorganic Cations ◽  
Large Pool ◽  
Inorganic Cation ◽  
Calcium Magnesium ◽  
Potassium Pyroantimonate

Potassium pyroantimonate, when used as fixative (saturated or half-saturated, without addition of any conventional fixative) has been demonstrated to produce intracellular precipitates of the insoluble salts of calcium, magnesium, and sodium and to preserve the general cell morphology. In both animal and plant tissues, the electron-opaque antimonate precipitates were found deposited in the nucleus—as well as within the nucleolus—and in the cytoplasm, largely at the site of the ribonucleoprotein particles; the condensed chromatin appeared relatively free of precipitates. The inorganic cations are probably in a loosely bound state since they are not retained by conventional fixatives. The implications of this inorganic cation distribution in the intact cell are discussed in connection with their anionic counterparts, i.e., complexing of cations by fixed anionic charges and the coexistence of a large pool of inorganic orthophosphate anions in the nucleus and nucleolus.

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