Hydrolysis kinetics of dissolved polymer substrates

2002 ◽  
Vol 45 (10) ◽  
pp. 99-104 ◽  
Author(s):  
W.T.M. Sanders ◽  
G. Zeeman ◽  
G. Lettinga
Keyword(s):  
Enzyme Activity ◽  
Laboratory Experiments ◽  
Hydrolysis Rate ◽  
Limiting Factor ◽  
Hydrolysis Kinetics ◽  
Parent Molecule ◽  
Polymer Substrates ◽  
Rate Limiting ◽  
Kinetics Of ◽  
Hydrolysis Of

In this paper, the relation between the hydrolysis rate of dissolved polymer substrates and sludge concentration was investigated in two ways, viz. by laboratory experiments and by computer simulations. In the simulations, the hydrolysis of dissolved polymer components was regarded as a general depolymerisation process in which the bonds of the parent molecule break randomly until only monomer and dimer components remain. The results illustrate that for the hydrolysis of dissolved polymer substrates the enzyme activity is the rate-limiting factor. Moreover, a general depolymerisation process can describe the enzymatic hydrolysis of these components.

scholarly journals Kinetics of Enzymatic Hydrolysis of Southeast Sulawesi Sago Starch

2020 ◽  
pp. 53-61
Author(s):  
Ansharullah Ansharullah ◽  
Muhammad Natsir
Keyword(s):  
Enzymatic Hydrolysis ◽  
Maximum Velocity ◽  
Enzyme Concentration ◽  
Hydrolysis Rate ◽  
Sago Starch ◽  
Optimum Conditions ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Substrate Concentrations ◽  
Menten Constant

The aims of this study were to characterize the kinetics of enzymatic hydrolysis of sago starch, obtained from Southeast Sulawesi Indonesia. The enzyme used for hydrolysis was bacterial ∝-amylase (Termamyl 120L from Bacillus licheniformis, E. C. 3.2.1.1).  The method to determine the initial velocity (Vo) of the hydrolysis was developed by differentiation a nonlinear equation (NLE).  The Vo of the hydrolysis was measured at various pH (6.0, 6.5,and 7.0), temperatures (40, 60, 75 and 95oC), enzyme concentrations (0.5, 1.0, 1.5 and 2.0 µg per mL) and in the presence of 70 ppm Ca++. The optimum conditions of this experiment were found to be at pH 6.5 – 7.0 and 75oC, and the Vo increased with increasing enzyme concentration. The Vo values at various substrate concentrations were also determined, which were then used to calculate the enzymes kinetics constant of the hydrolysis, including Michaelis-Menten constant (Km) and maximum velocity (Vmax) using a Hanes plot.  Km and Vmax values were found to be higher in the measurement at pH 7.0 and 75oC. The Km values  at four  different combinations of pH and temperatures (pH 6.5, 40oC; pH 6.5, 75oC; pH 7.0, 40oC; pH 7.0, 75oC) were found to be 0.86, 3.23, 0.77 and 3.83 mg/mL, respectively; and Vmax values were 17.5, 54.3, 20.3 and 57.1 µg/mL/min, respectively. The results obtained showed that hydrolysis rate of this starch was somewhat low.

scholarly journals Kinetic Analysis of the Hydrolysis of Pentose-1-Phosphates Through Apparent Nucleoside Phosphorolysis Equilibrium Shifts

2020 ◽  
Author(s):  
Felix Kaspar ◽  
Peter Neubauer ◽  
Anke Kurreck
Keyword(s):  
Kinetic Analysis ◽  
Hydrolysis Kinetics ◽  
Equilibrium Thermodynamics ◽  
Apparent Increase ◽  
Equilibrium Conversion ◽  
Sugar Phosphates ◽  
Kinetics Of ◽  
Hydrolysis Of

<div>Ask what an equilibrium can do for you:</div><div>Hydrolysis of pentose-1-phosphates leads to an apparent increase of the equilibrium conversion in nucleoside phosphorolysis reactions. This information can be leveraged via equilibrium thermodynamics to determine the hydrolysis kinetics of in situ generated sugar phosphates, which are known to be elusive and difficult to quantify.<br></div>

scholarly journals Dependence upon Bile Volume of the Biliary Excretion of Bromocresol Green and Amaranth in the Anaesthetized Rat

1975 ◽  
Vol 28 (4) ◽  
pp. 339 ◽  
Author(s):  
Alan G Clark ◽  
KarI M Rogers
Keyword(s):  
Biliary Excretion ◽  
Biliary Tree ◽  
Bulk Flow ◽  
Rate Equations ◽  
Bromocresol Green ◽  
Limiting Factor ◽  
Cumulative Volume ◽  
Rate Limiting ◽  
Kinetics Of ◽  
Anaesthetized Rat

The kinetics of the biliary excretion of both bromocresol green and amaranth are better described in terms of rate equations that are functions of the cumulative volume of bile excreted rather than of time. The rate of disappearance of bromocresol green from the liver also appears to depend on the volume of bile excreted rather than on time. It is proposed that bromocresol green, and probably also amaranth, rapidly equilibrates between the hepatic and biliary compartments as a result of reabsorption from the biliary tree and that the rate-limiting factor in the biliary excretion of these dyes is the removal of dye from the biliary tree by bulk flow.

scholarly journals Kinetics of alkoxysilanes hydrolysis: An empirical approach

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ahmed A. Issa ◽  
Marwa El-Azazy ◽  
Adriaan S. Luyt
Keyword(s):  
Reaction Mechanisms ◽  
Hydrolysis Reaction ◽  
Hydrolysis Rate ◽  
Coupling Agents ◽  
Linear Free Energy Relationship ◽  
Acidic Media ◽  
Linear Free Energy ◽  
Primary Materials ◽  
Kinetics Of ◽  
Hydrolysis Of

AbstractAlkoxysilanes and organoalkoxysilanes are primary materials in several industries, e.g. coating, anti-corrosion treatment, fabrication of stationary phase for chromatography, and coupling agents. The hydrolytic polycondensation reactions and final product can be controlled by adjusting the hydrolysis reaction, which was investigated under a variety of conditions, such as different alkoxysilanes, solvents, and catalysts by using gas chromatography. The hydrolysis rate of alkoxysilanes shows a dependence on the alkoxysilane structure (especially the organic attachments), solvent properties, and the catalyst dissociation constant and solubility. Some of the alkoxysilanes exhibit intramolecular catalysis. Hydrogen bonding plays an important role in the enhancement of the hydrolysis reaction, as well as the dipole moment of the alkoxysilanes, especially in acetonitrile. There is a relationship between the experimentally calculated polarity by the Taft equation and the reactivity, but it shows different responses depending on the solvent. It was found that negative and positive charges are respectively accumulated in the transition state in alkaline and acidic media. The reaction mechanisms are somewhat different from those previously suggested. Finally, it was found that enthalpy–entropy compensation (EEC) effect and isokinetic relationships (IKR) are exhibited during the hydrolysis of CTES in different solvents and catalysts; therefore, the reaction has a linear free energy relationship (LFER).

Hydrolysis Kinetics of Cornstalk in Formic Acid Solution

2012 ◽  
Vol 535-537 ◽  
pp. 2438-2441
Author(s):  
Jun Ping Zhuang ◽  
Xue Ping Li
Keyword(s):  
Activation Energy ◽  
Acid Solution ◽  
Formic Acid ◽  
Wood Fiber ◽  
Hydrolysis Kinetics ◽  
Practical Applications ◽  
And Performance ◽  
Promising Source ◽  
Kinetics Of ◽  
Hydrolysis Of

Cornstalk, among the agricultural residues and other non-wood fiber, is a more promising source of lignocellulosic materials for bioethanol production. Pretreatment is an essential step in the enzymatic hydrolysis of biomass and subsequent production of bioethanol. Kinetic models can have practical applications for the optimization of the process and performance analysis, or economic estimations, so investigate the cornstalk hydrolysis kinetics is necessary. In this paper, effects of temperature and time on cornstalk hydrolysis in saturated formic acid with 4% hydrochloric acid solution reaction kinetics have been investigated. The results showed that the hydrolysis velocities of cornstalk were 0.021 h−1 at 60 °C, 0.0302 h−1 at 65 °C and 0.060 h−1 at 70 °C, the degradation velocities of glucose were 0.061 h−1 at 60 °C, 0.0845 h−1 at 65 °C, and 0.24 h−1 at 70 °C, the activation energy of cornstalk hydrolysis was 99.60 kJ/mol, and the activation energy of glucose degradation was130.94 kJ/mol.

scholarly journals The kinetics of hydrolysis of some extended N-aminoacyl-l-arginine methyl esters by human plasma kallikrein. Evidence for subsites S2 and S3

1982 ◽  
Vol 203 (1) ◽  
pp. 149-153 ◽  
Author(s):  
P R Levison ◽  
G Tomalin
Keyword(s):  
Human Plasma ◽  
Methyl Esters ◽  
Plasma Kallikrein ◽  
Substrate Complex ◽  
Enzyme Substrate ◽  
Rate Limiting Step ◽  
Kinetics Of Hydrolysis ◽  
Rate Limiting ◽  
Kinetics Of ◽  
Hydrolysis Of

Subsites in the S2-S4 region were identified in human plasma kallikrein. Kinetic constants (kcat., Km) were determined for a series of seven extended N-aminoacyl-L-arginine methyl esters based on the C-terminal sequence of bradykinin (-Pro-Phe-Arg) or (Gly)n-Arg. The rate-limiting step for the enzyme-catalysed reaction was found to be deacylation of the enzyme. It was possible to infer that hydrogen-bonded interactions occur between substrate and the S2-S4 region of kallikrein. Insertion of L-phenylalanine at residue P2 demonstrates that there is also a hydrophobic interaction with subsite S2, which stabilizes the enzyme-substrate complex. The strong interaction demonstrated between L-proline at residue P3 and subsite S3 is of greatest importance in the selectivity of human plasma kallikrein. The purification of kallikrein from Cohn fraction IV of human plasma is described making use of endogenous Factor XIIf to activate the prekallikrein. Kallikreins I (Mr 91 000) and II (Mr 85 000) were purified 170- and 110-fold respectively. Kallikrein I was used for the kinetic work.

scholarly journals Large Peptide Permeation Through a Membrane Channel: Understanding Protamine Translocation Through CymA from Klebsiella Oxytoca

2020 ◽  
Author(s):  
Sushil Pangeni ◽  
Jigneshkumar Dahyabhai Prajapati ◽  
Jayesh Arun Bafna ◽  
Nilam Mohamed ◽  
Werner M. Nau ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Klebsiella Oxytoca ◽  
Limiting Factor ◽  
Membrane Channel ◽  
Voltage Dependent ◽  
Dynamics Simulations ◽  
Rate Limiting ◽  
Kinetics Of ◽  
Zero Voltage ◽  
Large Peptide

Quantifying the passage of the large peptide protamine (Ptm) across CymA, a passive channel for cyclodextrin uptake, is in the focus of this study. Using a reporter-pair based fluorescence membrane assay we detected the entry of Ptm into liposomes containing CymA. The kinetics of the Ptm entry was independent of its concentration suggesting that the permeation across CymA is the rate-limiting factor. Furthermore, we reconstituted single CymA channels into planar lipid bilayers and recorded the ion current fluctuations in the presence of Ptm. To this end, we were able to resolve the voltage-dependent entry of single Ptm peptide molecules into the channel. Extrapolation to zero voltage revealed about 1-2 events per second and long dwell times, in agreement with the liposome study. Applied-field and steered molecular dynamics simulations provided an atomistic view on the permeation. It can be concluded that a concentration gradient of 1 M Ptm leads to a translocation rate of about 1 molecule per second and per channel.

scholarly journals The substrate specificity of acid α-glucosidase from rabbit muscle

1971 ◽  
Vol 124 (4) ◽  
pp. 701-711 ◽  
Author(s):  
T. N. Palmer
Keyword(s):  
Substrate Inhibition ◽  
Physiological Role ◽  
Liver Glycogen ◽  
Rabbit Muscle ◽  
Ph Optimum ◽  
Enzyme Action ◽  
Rate Limiting ◽  
Kinetics Of ◽  
Hydrolysis Of

1. Acid α-glucosidase was purified 3500-fold from rabbit muscle. 2. The enzyme was activated by cations, the degree of activation varying with the substrate. Enzyme action on glycogen was most strongly activated and activation was apparently of a non-competitive type. With rabbit liver glycogen as substrate, the relative Vmax. increased 15-fold, accompanied by an increase in Km from 8.3 to 68.6mm-chain end over the cation range 2–200mm-Na+ at pH4.5. Action on maltose was only moderately activated (1.3-fold, non-competitively) and action on maltotriose was marginally and competitively inhibited. 3. The pH optimum at 2mm-Na+ was 4.5 (maltose) and 5.1 (glycogen). Cation activation of enzyme action on glycogen was markedly pH-dependent. At 200mm-Na+, the pH optimum was 4.8 and activity was maximally stimulated in the range pH4.5–3.3. 4. Glucosidase action on maltosaccharides was associated with pronounced substrate inhibition at concentrations exceeding 5mm. Of the maltosaccharides tested, the enzyme showed a preference for p-nitrophenyl α-maltoside (Km 1.2mm) and maltotriose (Km 1.8mm). The extrapolated Km for enzyme action on maltose was 3.7mm. 5. The macromolecular polysaccharide substrate glycogen differed from linear maltosaccharide substrates in the kinetics of its interaction with the enzyme. Activity was markedly dependent on pH, cation concentration and polysaccharide structure. There was no substrate inhibition. 6. The enzyme exhibited constitutive α-1,6-glucanohydrolase activity. The Km for panose was 20mm. 7. The enzyme catalysed the total conversion of glycogen into glucose. The hydrolysis of α-1,6-linkages was apparently rate-limiting during the hydrolysis of glycogen. 8. Enzyme action on glycogen and maltose released the α-anomer of d-glucose. 9. The results are discussed in terms of the physiological role of acid α-glucosidase in lysosomal glycogen catabolism.

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