Enzymatic dephosphorylation of retinyl monophosphate by rat liver

1986 ◽  
Vol 64 (9) ◽  
pp. 864-868
Author(s):  
Providencia Rodríguez ◽  
Olga Bello
Keyword(s):  
Phosphatase Activity ◽  
Rat Liver ◽  
Reaction Rate ◽  
Tween 80 ◽  
Maximum Reaction Rate ◽  
Dolichyl Phosphate ◽  
Maximum Reaction ◽  
Phosphorylated Compounds ◽  
Ph Range ◽  
Triton X

Rat liver has been shown to contain an enzyme that catalyzes the dephosphorylation of retinyl monophosphate. This activity was extracted with 0.1 M Tris buffer (pH 7.5). Maximum reaction rate was observed at a pH range of 7.0–7.5. It did not require metal ions for activity and was sensitive to fluoride ion. The retinyl monophosphate phosphatase activity was proportional to time and protein and substrate concentration. Triton X-100 (range of 0.05–0.10%) increased the activity 100%, whereas other detergents (Tween 80, cholate, and deoxycholate) did not activate the enzyme. A number of phosphorylated compounds tested as inhibitors of retinyl monophosphatase activity, such as glucose 6-phosphate (20 mM), glycerophosphate (20 mM), phosphatidic acid (8 mM), and dolichyl phosphate (3 mM), did not compete with retinyl monophosphate as substrate. However, at 20 mM concentration, ATP, ADP, 5′-AMP, and pyrophosphate were inhibitors of the enzyme. It is not possible at present to give further details about the specificity of the phosphatase activity. The enzyme described could play a regulatory role in retinol-mediated glycosylations, by altering the endogenous level of retinyl monophosphate.

A novel phytase from Citrobacter gillenii: characterization and expression in Pichia pastoris (Komagataella pastoris)

2020 ◽  
Author(s):  
Artur A Tkachenko ◽  
Anna N Kalinina ◽  
Larisa N Borshchevskaya ◽  
Sergey P Sineoky ◽  
Tatiana L Gordeeva
Keyword(s):  
Amino Acid ◽  
Pichia Pastoris ◽  
Amino Acid Sequence ◽  
Specific Activity ◽  
Gene Encoding ◽  
Maximum Reaction Rate ◽  
Maximum Reaction ◽  
Wide Ph Range ◽  
Recombinant Phytase ◽  
Ph Range

Abstract The phyCg gene encoding a new phytase from C. gillenii was optimized, synthesized, cloned, and expressed in Pichia pastoris. Analysis of the amino acid sequence of the enzyme showed that it belongs to the histidine acid phosphatase family. The amino acid sequence of the PhyCg phytase has the highest homology (73.49%) with a phytase sequence from Citrobacter braakii. The main characteristics for the purified recombinant phytase were established. The optimum pH and temperature were 4.5 and 50°C, respectively. The specific activity of the enzyme was 1577 U/mg. The Michaelis constant (Km) and the maximum reaction rate (Vmax) for sodium phytate were 0,185 mM and 2185 U/mg, respectively. The enzyme showed the pH and trypsin stability and had a high activity over a wide pH range.

scholarly journals Characterization of dolichol and dolichyl phosphate phosphatase from soya beans (Glycine max)

1983 ◽  
Vol 213 (2) ◽  
pp. 513-518 ◽  
Author(s):  
K Ravi ◽  
J W Rip ◽  
K K Carroll
Keyword(s):  
Enzyme Activity ◽  
Glycine Max ◽  
Phosphatidic Acid ◽  
Phosphatase Activity ◽  
Lysophosphatidic Acid ◽  
Competitive Inhibition ◽  
High Yield ◽  
Dolichyl Phosphate ◽  
Ability To Act ◽  
Phosphorylated Compounds

A series of polyprenols, ranging in length from 15 to 22 isoprene units, has been isolated from soya beans (Glycine max) and purified by high-pressure liquid chromatography. N.m.r., i.r. and mass spectra of the compounds indicated that they are alpha-saturated polyprenols of the dolichol type. The amount present in dry seeds was about 9 mg/100 g, whereas dolichyl phosphate (Dol-P) was present only in trace amounts. Dol-P phosphatase activity was detected in the microsomal fraction of 5-day-old germinating soya-bean cotyledons. The Dol-P phosphatase activity was linear with respect to time and protein concentration and exhibited a broad pH optimum (pH 7-9). Triton X-100 was necessary for significant enzyme activity. Enzyme activity was slightly enhanced by EDTA, whereas dithiothreitol was without effect. An apparent Km of 5 microM was determined for Dol-P. Bivalent metal ions were not required for enzyme activity. A number of phosphorylated compounds tested as enzyme substrates (including a number of nucleoside phosphates, glucose 6-phosphate, sodium β 1 leads to 4Glc. Because of the ease of purification of the enzyme and high yield in the absence of contaminating glycosidases and proteinases, Bacteroides fragilis is a valuable source of endo-beta-galactosidase for the structural analysis of carbohydrate chains. -glycerophosphate and Na4P2O7) did not compete with [1-3H]Dol-P as substrate. A number of phospholipids were also tested for their ability to act as Dol-P phosphatase substrates. At 1 mM concentration, phosphatidylcholine, phosphatidylethanolamine, phosphatidic acid and lysophosphatidic acid each inhibited enzymic activity. However, at 0.1 mM concentration, phosphatidylcholine and phosphatidylethanolamine were slightly stimulatory, whereas phosphatidic acid and lysophosphatidic acid were still inhibitory. Phosphatidic acid showed competitive inhibition.

Biodegradation of 2,4-dichlorophenol in a fluidized bed reactor with immobilized Phanerochaete chrysosporium

2010 ◽  
Vol 62 (4) ◽  
pp. 947-955 ◽  
Author(s):  
Xiao-ming Li ◽  
Qi Yang ◽  
Ying Zhang ◽  
Wei Zheng ◽  
Xiu Yue ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Phanerochaete Chrysosporium ◽  
Reaction Rate ◽  
Immobilized Cells ◽  
Fluidized Bed Reactor ◽  
Degradation Process ◽  
Maximum Reaction Rate ◽  
Monod Equation ◽  
Continuous Bioreactor ◽  
Maximum Reaction

The performance of a fluidized bed reactor using immobilized Phanerochaete chrysosporium to remove 2,4-dichlorophenol (2,4-DCP) from aqueous solution was investigated. The contribution of lignin peroxidase (LiP) and manganese peroxidase (MnP) secreted by Phanerochaete chrysosporium to the 2,4-DCP degradation was examined. Results showed that Lip and Mnp were not essential to 2,4-DCP degradation while their presence enhanced the degradation process and reaction rate. In sequential batch experiment, the bioactivity of immobilized cells was recovered and improved during the culture and the maximum degradation rate constant of 13.95 mg (Ld)−1 could be reached. In continuous bioreactor test, the kinetic behavior of the Phanerochaete chrysosporium immobilized on loofa sponge was found to follow the Monod equation. The maximum reaction rate was 7.002 mg (Lh)−1, and the saturation constant was 26.045 mg L−1.

Basic Studies on Anaerobic Degradation of Glucose in Continuous Stirred Tank Reactors

1991 ◽  
Vol 24 (5) ◽  
pp. 141-147
Author(s):  
Michimasa Nakamura ◽  
Atsushi Sakai ◽  
Jun'ichiro Matsumoto
Keyword(s):  
Anaerobic Degradation ◽  
Volatile Fatty Acid ◽  
Reaction Rate ◽  
Ph Value ◽  
Reaction Rate Constant ◽  
The Other ◽  
Total Volatile ◽  
Maximum Reaction Rate ◽  
Maximum Reaction ◽  
Total Volatile Fatty Acid

The two series of the characteristics of anaerobic degradation of low glucose concentrations were investigated. In the first series, the pH value in each reactor was not controlled. In the second series, the pH value in each reactor was controlled in the range of 6.9–7.2, by adding sodium bicarbonate into each influent. The ORP value was depressed by controlling the pH value of each reactor from acid range to approximately neutral range. In the pH uncontrolled series, the pH value in outflow decreased with increasing glucose concentration. In the pH uncontrolled series, produced total volatile fatty acid was about 70 to 550 mg/l; on the other hand, in pH controlled series, produced total volatile fatty acid was about 50 mg/l to 350 mg/l. The highest concentrations of acids formed were acetic acids, the second highest formed were propionic acids, the last formed were butyric acids. In the pH uncontrolled series, the maximum reaction rate constant Vm was 0.749 gCOD/gVS · day and the saturation constant Ks = 0.435 g/l. On the other hand, in the pH controlled series, the maximum reaction rate constant Vm was 1.441 gCOD/gVS · day and the saturation constant Ks = 0.739 g/l. Thus by controlling the pH value of the reactor, the activities of the anaerobic bacteria were much enhanced.

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