Identification of the Catalytic Base for Alcohol Activation in Choline Oxidase

Biochemistry ◽  
2014 ◽  
Vol 54 (2) ◽  
pp. 413-421 ◽  
Author(s):  
Crystal Smitherman ◽  
Kunchala Rungsrisuriyachai ◽  
Markus W. Germann ◽  
Giovanni Gadda
Keyword(s):  
Choline Oxidase ◽  
Alcohol Activation

scholarly journals Morpho-Physiological Testing of NaCl Sensitivity of Tobacco Plants Overexpressing Choline Oxidase Gene

Plants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1102
Author(s):  
Galina N. Raldugina ◽  
Sergey V. Evsukov ◽  
Liliya R. Bogoutdinova ◽  
Alexander A. Gulevich ◽  
Ekaterina N. Baranova
Keyword(s):  
Choline Oxidase ◽  
Culture Methods ◽  
Gene Encoding ◽  
Oxidase Gene ◽  
Bacterial Enzyme ◽  
Transgenic Lines ◽  
High Regeneration ◽  
Whole Plants ◽  
Implicit Response

In this study the transgenic lines (TLs) of tobacco (Nicotianatabacum L.), which overexpress the heterologous gene encoding the bacterial enzyme choline oxidase were evaluated. The goal of our work is to study the effect of choline oxidase gene expression on the sensitivity of plant tissues to the action of NaCl. The regenerative capacity, rhizogenesis, the amount of photosynthetic pigments and osmotically active compounds (proline and glycine betaine) were assessed by in vitro cell culture methods using biochemical and morphological parameters. Transgenic lines with confirmed expression were characterized by high regeneration capacity from callus in the presence of 200 mmol NaCl, partial retention of viability at 400 mmol NaCl. These data correlated with the implicit response of regenerants and whole plants to the harmful effects of salinity. They turned out to be less sensitive to the presence of 200 mmol NaCl in the cultivation medium, in contrast to the WT plants.

scholarly journals Highly Sensitive Fluorescent Detection of Acetylcholine Based on the Enhanced Peroxidase-Like Activity of Histidine Coated Magnetic Nanoparticles

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1207
Author(s):  
Hong Jae Cheon ◽  
Quynh Huong Nguyen ◽  
Moon Il Kim
Keyword(s):  
Magnetic Nanoparticles ◽  
High Sensitivity ◽  
High Specificity ◽  
Choline Oxidase ◽  
Fluorescent Detection ◽  
One Pot ◽  
Site Structure ◽  
Specificity And Sensitivity ◽  
Highly Sensitive ◽  
Peroxidase Mimics

Inspired by the active site structure of natural horseradish peroxidase having iron as a pivotal element with coordinated histidine residues, we have developed histidine coated magnetic nanoparticles (His@MNPs) with relatively uniform and small sizes (less than 10 nm) through one-pot heat treatment. In comparison to pristine MNPs and other amino acid coated MNPs, His@MNPs exhibited a considerably enhanced peroxidase-imitating activity, approaching 10-fold higher in catalytic reactions. With the high activity, His@MNPs then were exploited to detect the important neurotransmitter acetylcholine. By coupling choline oxidase and acetylcholine esterase with His@MNPs as peroxidase mimics, target choline and acetylcholine were successfully detected via fluorescent mode with high specificity and sensitivity with the limits of detection down to 200 and 100 nM, respectively. The diagnostic capability of the method is demonstrated by analyzing acetylcholine in human blood serum. This study thus demonstrates the potential of utilizing His@MNPs as peroxidase-mimicking nanozymes for detecting important biological and clinical targets with high sensitivity and reliability.

scholarly journals STUDIES ON THE STABILITY OF THE CHOLINE OXIDASE

1950 ◽  
Vol 185 (2) ◽  
pp. 731-739
Author(s):  
G.S. Eadie ◽  
Frederick. Bernheim
Keyword(s):  
Choline Oxidase ◽  
The Stability

Intracellular distribution of enzymes

1953 ◽  
Vol 141 (904) ◽  
pp. 420-433 ◽  
Keyword(s):  
Mitochondrial Fraction ◽  
Integrated System ◽  
Choline Oxidase ◽  
Optical Methods ◽  
Mitochondrial Activity ◽  
Permeability Barrier ◽  
Glutamic Dehydrogenase ◽  
Tissue Homogenates ◽  
Distribution Studies ◽  
Apparent Distribution

The localization of enzymes in cells may be studied by the differential centrifugation of tissue homogenates. This method has been used to study the distribution of L-malic and L-glutamic dehydrogenases, choline oxidase, adenosinetriphosphatase, and also of the nucleic acids and nitrogen between the fractions of the homogenate. L-Glutamic dehydrogenase is entirely m itochondrial, and malicdehydrogenase is shared almost equally, between the mitochondria and the supernatant although the true mitochondrial activity is not apparent unless unmasked, e. g. by water disruption. In the absence of this precaution intact mitochondria show only a small proportion of the activity of the whole homogenate. Choline oxidase is almost entirely mitochondrial, and adenosine triphosphatase has a large representation in all the particulate fractions. In our experiments we have found that the ribonucleic acid content of the mitochondria is higher than previously reported. Distribution studies of enzymes are misleading unless it can be shown that the methods employed are valid for all the fractions studied, and our evidence shows that serious errors of in terpretation may arise unless more than one method of determination is used. In particular, the physical state of the mitochondria affects their apparent enzyme content, as shown by the; investigation of malic and glutamic dehydrogenases by manometric and optical methods. This anomaly is due to an ‘accessibility barrier’ or ‘permeability barrier’ present in intact mitochondria, which hinders the entry of coenzyme I. In an integrated system composed of several enzymes, the rate of the whole reaction may be limited by the rate of any one of the intermediate steps. Thus intact mitochondria fail to develop their maximum oxygen up take with several substrates unless a continuous supply of phosphate acceptor is ensured. Otherwise the rate of transfer of phosphate limits the whole reaction, reducing the apparent activity of the mitochondrial fraction relative to that of the whole homogenate, and hence the apparent distribution of enzyme. Similarly, the activity of the choline oxidase of the mitochondrial fraction is more sensitive to pH changes than that of the whole homogenate so that at pH 6·8, 80% of the homogenate activity may be recovered in the mitochondria, whereas at pH 7·8, the recovery is only 50%. At pH 7·8 full activity of the mitochondria, and a recovery of over 80%, may be achieved by the addition of coenzyme I.

scholarly journals STUDIES ON RAT LIVER CHOLINE OXIDASE: AN ASSAY METHOD

1951 ◽  
Vol 192 (1) ◽  
pp. 73-80 ◽  
Author(s):  
J.N. Williams ◽  
Gerald. Litwack ◽  
C.A. Elvehjem
Keyword(s):  
Rat Liver ◽  
Choline Oxidase ◽  
Assay Method

scholarly journals Assay of Phospholipase D Activity by an Amperometric Choline Oxidase Biosensor

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1304 ◽  
Author(s):  
Rosanna Ciriello ◽  
Antonio Guerrieri
Keyword(s):  
Phospholipase D ◽  
Limit Of Detection ◽  
High Sensitivity ◽  
Fast Response ◽  
Borate Buffer ◽  
Choline Oxidase ◽  
Linear Calibration ◽  
Real Sample Analysis ◽  
Polypyrrole Film ◽  
Overoxidized Polypyrrole

A novel electrochemical method to assay phospholipase D (PLD) activity is proposed based on the employment of a choline biosensor realized by immobilizing choline oxidase through co-crosslinking on an overoxidized polypyrrole film previously deposited on a platinum electrode. To perform the assay, an aliquot of a PLD standard solution is typically added to borate buffer containing phosphatidylcholine at a certain concentration and the oxidation current of hydrogen peroxide is then measured at the rotating modified electrode by applying a detection potential of +0.7 V vs. SCE. Various experimental parameters influencing the assay were studied and optimized. The employment of 0.75% (v/v) Triton X-100, 0.2 mM calcium chloride, 5 mM phosphatidylcholine, and borate buffer at pH 8.0, ionic strength (I) 0.05 M allowed to achieve considerable current responses. In order to assure a controlled mass transport and, at the same time, high sensitivity, an electrode rotation rate of 200 rpm was selected. The proposed method showed a sensitivity of 24 (nA/s)⋅(IU/mL)−1, a wide linear range up to 0.33 IU/mL, fast response time and appreciable long-term stability. The limit of detection, evaluated from the linear calibration curve, was 0.005 IU/mL (S/N = 3). Finally, due to the presence of overoxidized polypyrrole film characterized by notable rejection properties towards electroactive compounds, a practical application to real sample analysis can be envisaged.

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