Influence of substrate concentration on the activation of transketolase, aspartate aminotransferase, and glutathione reductase by coenzymes.

1984 ◽  
Vol 30 (1) ◽  
pp. 143-144
Author(s):  
J C Hafkenscheid ◽  
C M van Dijk
Keyword(s):  
Catalytic Activity ◽  
Glutathione Reductase ◽  
Aspartate Aminotransferase ◽  
Substrate Concentration ◽  
Activity Concentrations ◽  
Influence Of Substrate ◽  
Underlying Mechanisms ◽  
Substrate Concentrations

Abstract We investigated the mechanism by which the three most commonly measured enzymes in erythrocytes are activated by their respective coenzymes by determining the catalytic activity concentrations of transketolase (EC 2.2.1.1), aspartate aminotransferase (EC 2.6.1.1), and glutathione reductase (EC 1.6.4.2) in relation to various substrate concentrations. We conclude that the underlying mechanisms by which the enzymes are activated are not the same.

Changes in mass and catalytic activity concentrations of aspartate aminotransferase isoenzymes in serum after a myocardial infarction.

1986 ◽  
Vol 32 (3) ◽  
pp. 496-500 ◽  
Author(s):  
A E Niblock ◽  
G Jablonsky ◽  
F Y Leung ◽  
A R Henderson
Keyword(s):  
Myocardial Infarction ◽  
Enzyme Activity ◽  
Catalytic Activity ◽  
Aspartate Aminotransferase ◽  
Left Ventricular ◽  
Peak Activity ◽  
Ventricular Failure ◽  
Total Enzyme Activity ◽  
Activity Concentrations ◽  
Total Enzyme

Abstract We used an RIA and inhibition of enzyme activity to monitor the changes in mass and catalytic concentrations of the aspartate aminotransferase (EC 2.6.1.1;AST) isoenzymes in serum after myocardial infarction. Cytosolic (c-AST) and mitochondrial (m-AST) forms of AST were present in sera from all 38 of our patients. Although the immunological and catalytic concentrations of both isoenzymes correlated well with the size of the infarct, c-AST gave a better measure than did m-AST. About 20% of the total enzyme activity at peak activity was from the mitochondrial isoenzyme. Both isoenzyme activities peak at very nearly the same time, but m-AST has the longer half-life. Immunological evidence of the mitochondrial isoenzyme can be detected in serum for at least eight days after the infarct. The presence of left ventricular failure produces greater serum isoenzyme activities than in those without failure.

Effects of substrate concentration on results of determination of prostatic acid phosphatase with thymolphthalein monophosphate.

1983 ◽  
Vol 29 (1) ◽  
pp. 148-151 ◽  
Author(s):  
A Kessner ◽  
E J Woodard ◽  
G N Bowers
Keyword(s):  
Catalytic Activity ◽  
Acid Phosphatase ◽  
Substrate Concentration ◽  
Prostatic Acid Phosphatase ◽  
Combined Effects ◽  
Mixed Substrate ◽  
Order Of Magnitude ◽  
Substrate Concentrations

Abstract The relation between concentration of thymolphthalein monophosphate substrate and catalytic activity was investigated for the determination of prostatic acid phosphatase. This study, an extension of previously reported work (Clin. Chem. 27: 1372, 1981), shows that lot-to-lot variation in purity of thymolphthalein monophosphate preparations is reflected in substrate-velocity curves. Plateau regions in these curves at 1.5-2.5 g/L result from the combined effects of (a) substrate concentrations that are an order of magnitude below Km and (b) a further decrease in available substrate caused by formation of substrate aggregates in the presence of serum. To simplify the identification of superior lots of thymolphthalein monophosphate, we give a mixed-substrate protocol for testing different lots.

Multiplication of a Klebsiella pneumoniae Strain in Water at Low Concentrations of Substrates

1988 ◽  
Vol 20 (11-12) ◽  
pp. 117-123 ◽  
Author(s):  
D. van der Kooij ◽  
W. A. M. Hijnen
Keyword(s):  
Amino Acids ◽  
Water Treatment ◽  
Klebsiella Pneumoniae ◽  
Substrate Concentration ◽  
Treatment System ◽  
Water Treatment System ◽  
Low Concentrations ◽  
Ks Values ◽  
Substrate Concentrations

A K.pneumoniae strain, isolated from a water treatment system, was tested in growth measurements for its ability to multiply at substrate concentrations of a few micrograms per liter. The organism multiplied on mixtures of carbohydrates and amino acids at a substrate concentration of 1 µg of C of each compound per liter. Tests with individual compounds revealed that especially carbohydrates were utilized at low concentrations. The Ks values obtained for maltose and maltopentaose were 53 µg of C/l and 114 µg of C per liter, respectively. The significance of the growth of K.pneumoniae at low substrate concentrations is discussed.

scholarly journals The determination of binding parameters when the total and free substrate concentrations are not approximately equal

1979 ◽  
Vol 179 (3) ◽  
pp. 697-700 ◽  
Author(s):  
N Gains
Keyword(s):  
Substrate Concentration ◽  
Graphical Method ◽  
Enzyme Concentration ◽  
Binding Parameters ◽  
Free Concentration ◽  
Equilibrium Binding ◽  
Substrate Concentrations

By using a standard graphical method values of Km and V may be found that are independent of the conditions and assumptions that the total substrate concentration approximates to its free concentration and that Km is much larger than the enzyme concentration. The procedure is also applicable to the determination of equilibrium binding parameters of a ligand to a macromolecule.

Modeling of the enzymatic kinetic synthesis of cephalexin-Influence of substrate concentration and temperature

2001 ◽  
Vol 73 (3) ◽  
pp. 171-178 ◽  
Author(s):  
C. G. P. H. Schroën ◽  
V. A. Nierstrasz ◽  
H. M. Moody ◽  
M. J. Hoogschagen ◽  
P. J. Kroon ◽  
...  
Keyword(s):  
Substrate Concentration ◽  
Influence Of Substrate

scholarly journals Graphical Approach to Compare Concentration Constants of Hill and Michaelis-Menten Equations

2018 ◽  
Vol 1 (3) ◽  
pp. 94-99 ◽  
Author(s):  
Elena V. Emelyanova
Keyword(s):  
Catalytic Activity ◽  
Substrate Concentration ◽  
Hill Equation ◽  
Enzymatic Process ◽  
Michaelis Constant ◽  
Graphical Approach ◽  
Graphical Technique ◽  
Kinetics Of ◽  
Permissible Rate ◽  
Concentration Constants

The aim of present study was to describe the graphical technique how to go from Hill concentration constant to Michaelis constant. To compare enzymatic processes, the kinetics of which is subjected to different regularities, it is possible to use constants that characterize catalytic activity (Vmax) and concentration constants that are the substrate concentration at which the rate of the enzymatic process is equal to a half of maximum permissible rate. Concentration constants are S0.5 for Hill equation and Km for Michaelis-Menton equation. The graphical approach was proposed in order to go from concentration constant of Hill equation to Michaelis concentration of the process that could be characterized by the same catalytic activity (the same values of minimum and maximum rates) similar to that observed in the process described by Hill equation.

Effective Substrate Loading for Saccharification of Corn Cob and Concurrent Production of Lignocellulolytic Enzymes by Fusarium oxysporum and Sporothrix carnis

2020 ◽  
Vol 8 (2) ◽  
pp. 109-115
Author(s):  
Folasade M. Olajuyigbe ◽  
Cornelius O. Fatokun ◽  
Oluwatosin I. Oni
Keyword(s):  
Fusarium Oxysporum ◽  
Substrate Concentration ◽  
Reducing Sugars ◽  
Cost Effective ◽  
Reducing Sugar ◽  
Lignocellulolytic Enzymes ◽  
Corn Cob ◽  
Lignocellulosic Wastes ◽  
Single Process ◽  
Substrate Concentrations

Background: One of the critical challenges of cost-effective bioethanol production from lignocellulosic biomass is the decreasing yield of reducing sugars caused by increasing substrate loading. Hence, it is crucial to determine the best substrate concentration for efficient saccharification of lignocellulosic wastes. Objective: This paper reports the saccharification of corn cob by two lignocellulolytic fungi (Fusarium oxysporum and Sporothrix carnis) and concurrent production of lignocellulolytic enzymes at varying substrate concentrations. Methods: F. oxysporum and S. carnis were cultivated on corn cob based media at 30°C and 160 rpm for 144 h. The lignocellulosic composition of corn cob was determined. Saccharification of varying concentrations of substrate was determined by evaluating the release of reducing sugar while the production of cellulase and xylanase was monitored. Results: Cellulose, hemicellulose and lignin contents of corn cob were 37.8±1.56%, 42.2±1.68% and 12.7±1.23%, respectively. Yields of reducing sugar by F. oxysporum and S. carnis were 5.03 µmol/mL and 6.16 µmol/mL; and 6.26 µmol/mL and 6.58 μmol/mL at 10.0 and 25.0% substrate concentration, respectively. The production of cellulase and xylanase was exponential as corn cob concentration increased from 0.5% to 10.0% yielding 586.93 U/mL and 1559.18 U/mL from F. oxysporum, with 590.7 U/mL and 1573.95 U/mL from S. carnis, respectively. Conclusion: The study shows that the most efficient saccharification of corn cob by F. oxysporum and S. carnis was achieved at 10.0% substrate concentration. This suggests that two separate saccharification processes at this concentration will result in higher yields of enzyme and reducing sugars than a single process involving higher concentration.

Sign in / Sign up

Export Citation Format

Share Document