Long chain ß-aminoethanols as micellar catalysts for the hydrolysis of diphenyl-p-nitrophenyl phosphate. The observation of an unusual enhancement of catalysis in the presence of added polyols

1999 ◽  
Vol 77 (10) ◽  
pp. 1577-1588
Author(s):  
H Oumar-Mahamat ◽  
H Slebocka-Tilk ◽  
R S Brown
Keyword(s):  
Ethylene Glycol ◽  
Aqueous Media ◽  
Polyethylene Glycol 400 ◽  
Ph Values ◽  
Peg 400 ◽  
Nitrophenyl Phosphate ◽  
Aqueous Ethylene Glycol ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Long Chain

The hydrolysis of p-nitrophenyldiphenyl phosphate (PNPDPP, 7) catalyzed by N-dodecylaminoethanol (6a), N-tetradecylaminoethanol (6b), N-methyl-N-tetradecylaminoethanol (6c), and N-hexadecylaminoethanol (6d) was investigated at 25°C at various pH values in aqueous media containing additives. Added ethanol or dimethoxyethane produces very little activity of 6a, b, c toward 7. The highest activities of 6a, b were found at pH 8.0 and 8.5 in solvents containing 20% glycerol or ethylene glycol. Under no conditions was N-hexadecylaminoethanol (6d) found to be active. The kinetics of the reaction of 6b with 7 were also investigated in a medium containing various amounts of glycerol, polyethylene glycol 400 (PEG 400), and water at pH 7.6-8.5. The best catalytic system comprised 3 mM 6b in 20% aqueous ethylene glycol, pH 8.5, which accelerated the hydrolysis of 7 by 1700-fold over the blank rate. Kinetic experiments conducted using [7]/[6b] = 1 and 2 demonstrate that 6b exhibits true turnover catalysis. A mechanism for the catalyzed reaction is proposed.Key words: ß-aminoethanols, hydrolysis, p-nitrophenyldiphenyl phosphate, micelles, polyhydroxy alcohols.

scholarly journals Cryoenzymology of trypsin. A detailed kinetic study of the trypsin-catalysed hydrolysis of N-α-benzyloxycarbonyl-l-lysine p-nitrophenyl ester at low temperatures

1983 ◽  
Vol 215 (3) ◽  
pp. 555-563 ◽  
Author(s):  
J P G Malthouse ◽  
A I Scott
Keyword(s):  
Aqueous Media ◽  
Side Chain ◽  
Ambient Temperatures ◽  
Ph Values ◽  
Mechanism Of Catalysis ◽  
The Individual ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Nitrophenyl Ester ◽  
Positively Charged

A detailed study of the kinetics of the trypsin (EC 3.4.21.4)-catalysed hydrolysis of N-alpha-benzyloxycarbonyl-L-lysine p-nitrophenyl ester in cryosolvents at 0 degrees C and below was undertaken. The pH-dependences of kcat, Km, k+2, k+3 and Ks were determined under cryoenzymological conditions and are compared with previous results [Antonini & Ascenzi (1981) J. Biol. Chem. 256, 12449-12455] obtained in fully aqueous media at ambient temperatures. Below pH 5.0 the kinetics, and presumably the mechanism of catalysis, are not significantly perturbed under cryoenzymological conditions. However, it is shown that below pH 5.0 both Km and Ks are decreased under these conditions but that both are increased at pH 6.7 relative to the results obtained in fully aqueous media at ambient temperatures. The effects of the cryoenzymological conditions on the individual catalytic parameters are discussed. The acylation rate constant, k+2, is essentially constant at pH 4.2 and 5.0 but decreases at lower pH values with an apparent pKa of approx. 4.0. In view of the low enthalpy of ionization associated with this pKa it is suggested that this group is the carboxy group of aspartic acid-189, which binds the positively charged lysine side chain of the substrate. The mechanistic implications of the results for the acylation step are discussed. It is also shown that only at low pH values can significant amounts of acylated trypsin be accumulated.

scholarly journals Phosphatase synthesis in Klebsiella (Aerobacter) aerogenes growing in continuous culture

1972 ◽  
Vol 127 (1) ◽  
pp. 87-96 ◽  
Author(s):  
P. G. Bolton ◽  
A. C. R. Dean
Keyword(s):  
Alkaline Phosphatase ◽  
Acid Phosphatase ◽  
Continuous Culture ◽  
Activity Profile ◽  
Glucose Effect ◽  
Ph Values ◽  
Nitrophenyl Phosphate ◽  
Wide Range ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

1. Phosphatase synthesis was studied in Klebsiella aerogenes grown in a wide range of continuous-culture systems. 2. Maximum acid phosphatase synthesis was associated with nutrient-limited, particularly carbohydrate-limited, growth at a relatively low rate, glucose-limited cells exhibiting the highest activity. Compared with glucose as the carbon-limiting growth material, other sugars not only altered the activity but also changed the pH–activity profile of the enzyme(s). 3. The affinity of the acid phosphatase in glucose-limited cells towards p-nitrophenyl phosphate (Km 0.25–0.43mm) was similar to that of staphylococcal acid phosphatase but was ten times greater than that of the Escherichia coli enzyme. 4. PO43−-limitation derepressed alkaline phosphatase synthesis but the amounts of activity were largely independent of the carbon source used for growth. 5. The enzymes were further differentiated by the effect of adding inhibitors (F−, PO43−) and sugars to the reaction mixture during the assays. In particular, it was shown that adding glucose, but not other sugars, stimulated the rate of hydrolysis of p-nitrophenyl phosphate by the acid phosphatase in carbohydrate-limited cells at low pH values (<4.6) but inhibited it at high pH values (>4.6). Alkaline phosphatase activity was unaffected. 6. The function of phosphatases in general is discussed and possible mechanisms for the glucose effect are outlined.

Kinetics of acid-assisted hydrolysis of pentachlorophenol in aqueous media

2008 ◽  
Vol 49 (3) ◽  
pp. 361-365 ◽  
Author(s):  
S. M. Kulikov ◽  
B. J. R. Holder
Keyword(s):  
Aqueous Media ◽  
Kinetics Of ◽  
Hydrolysis Of

A pulse radiolysis study of trapped electrons in aqueous ethylene glycol glasses

1983 ◽  
Vol 61 (1) ◽  
pp. 189-193 ◽  
Author(s):  
Zhennan Wu ◽  
Norman V. Klassen ◽  
Hugh A. Gillis ◽  
George G. Teather
Keyword(s):  
Ethylene Glycol ◽  
Reaction Kinetics ◽  
Pulse Radiolysis ◽  
Trapped Electrons ◽  
Aqueous Ethylene Glycol ◽  
The Stability ◽  
Kinetics Of

The yield and reaction kinetics of trapped electrons, [Formula: see text] and [Formula: see text], in several ethylene glycol/D2O glasses have been studied from 6–72 K by pulse radiolysis. An increased D2O concentration is believed to increase the concentration of IR-traps thereby leading to a greater [Formula: see text] and to decrease the concentration of VIS-traps thereby increasing the stability of [Formula: see text]. The yield and stability of [Formula: see text] are also increased by lowering the temperature. A redetermination of [Formula: see text] (1.3 × 104 M−1 cm−1 at 1800 nm) confirms earlier values.

THE NON-ENZYMATIC HYDROLYSIS OF p-NITROPHENYL PHOSPHATE

1958 ◽  
Vol 36 (4) ◽  
pp. 686-690 ◽  
Author(s):  
K. A. Holbrook ◽  
Ludovic Ouellet
Keyword(s):  
Activation Energy ◽  
Enzymatic Hydrolysis ◽  
Ionic Species ◽  
Kcal Mole ◽  
First Order ◽  
Colorimetric Measurement ◽  
Nitrophenyl Phosphate ◽  
Ph Range ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of the non-enzymatic hydrolysis of p-nitrophenyl phosphate have been studied in aqueous solution in the pH range 2.6 to 9.0 and at temperatures from 68.0°to 82.0 °C. The reaction has been followed by colorimetric measurement of the nitrophenol produced by the reaction[Formula: see text]The reaction is first order with respect to p-nitrophenyl phosphate and has an activation energy of 26.0 kcal./mole at pH 2.6. An explanation has been proposed in terms of the different rates of hydrolysis of the various ionic species of the ester present in solution.

Polygalacturonases of Aspergillus flavipes FP-500: A Kinetic Analysis of Batch Culture Systems Based on Unstructured Models

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Maria Aurora Martinez Trujillo ◽  
Juan S. Aranda Barradas ◽  
Guillermo Aguilar Osorio
Keyword(s):  
Galacturonic Acid ◽  
Culture Media ◽  
Culture Conditions ◽  
Batch Cultures ◽  
Ph Values ◽  
Aspergillus Flavipes ◽  
Production Kinetics ◽  
Pectinolytic Enzymes ◽  
Kinetics Of ◽  
Hydrolysis Of

Abstract Pectin is a widespread complex heteropolysaccharide contained in plants cell wall. The hydrolysis of this natural-occurring polymer is an important process both in food industry and pectin-rich wastewater treatment. Although pectin-degrading enzymes have been produced classically by microbial mold strains, production kinetics of the involved endo- and exo- pectinolytic enzymes is still a challenge in industrial microbiology. In order to assess the pectinases production kinetics, the strain Aspergillus flavipes FP-500 was grown in batch cultures using pectin, glucose or galacturonic acid as limiting substrates. Unstructured models were useful for describing the experimental behavior, and for estimating the kinetic parameters associated to the Logistic, Monod and Luedeking-Piret models. Our results pointed out that the exopolygalacturonases production is basically non-growth associated, suggesting an inducible nature for some exo- isoenzymes and endopolygalacturonases, even if some constitutive activity is postulated. Besides, to identify the combined effect of carbon source and pH on polygalacturonases production, several experiments were developed at different pH culture conditions. Exopectinases produced on glucose were inhibited by culture media acidification, while on galacturonic acid these enzymes are produced mainly at pH values of 5.0 or higher. Exopectinases production on pectin was not importantly affected by the established pH values during the culture. Endopectinases were produced basically at acidic conditions on pectin, but growth on galacturonic acid showed a strong inducing effect on endopectinases at pH 5.0

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