On the effectiveness factor of immobilized enzymes with linear mixed-type product inhibition kinetics

By a study of the product-inhibition kinetics of the octanoyl-CoA synthetase from ox liver mitochondria, evidence was obtained consistent with the hypothesis that the enzyme reacts by a Bi Uni Uni Bi Ping Pong type of mechanism in which the order of addition and evolution of substrates and products is CoA, octanoate, octanoyl-CoA, ATP, PPi and AMP. There is also evidence that more than one molecule of CoA can add to the enzyme and that it may act as an allosteric activator.

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Inhibition Mechanism and Kinetic Model for Ozagrel on Mushroom Tyrosinase

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.236-238.2913 ◽

2011 ◽

Vol 236-238 ◽

pp. 2913-2916

Author(s):

Bai Li Shu ◽

Ya Juan Fan ◽

Qi Meng Zhang ◽

Ying Li Liu ◽

Yue Gu

Keyword(s):

Kinetic Model ◽

Mixed Type ◽

Kinetic Method ◽

Inhibition Mechanism ◽

Mushroom Tyrosinase ◽

Inhibition Kinetics ◽

Antithrombotic Drug ◽

Substrate Complex ◽

Mixed Type Inhibitor

This investigation shows that ozagrel, an antithrombotic drug, can inhibit mushroom tyrosinase well. The IC50 value was 3.45 mmol/L. Ozagrel was estimated to be a reversible mixed-type inhibitor of mushroom tyrosinase by Lineweaver-Burk plots. The inhibition kinetics has been studied by using the kinetic method of the substrate reaction described by Tsou. The constants of tyrosinase and tyrosinase-substrate complex inhibited by 1.0 mmol/L ozagrel have been determined to be 87.28 and 66.07 µmol/L, respectively.

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Evaluation of effectiveness factor of immobilized enzymes using Runge-Kutta-Gill method: how to solve mathematical undetermination at particle center point?

Bioprocess Engineering ◽

10.1007/s004490050579 ◽

1999 ◽

Vol 20 (2) ◽

pp. 185 ◽

Cited By ~ 8

Author(s):

S. C. Oliveira

Keyword(s):

Immobilized Enzymes ◽

Effectiveness Factor ◽

Particle Center ◽

Center Point ◽

Runge Kutta

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Some properties of the NADP-specific malic enzyme from the moderate Halophile Vibrio Costicola

Canadian Journal of Microbiology ◽

10.1139/m80-008 ◽

1980 ◽

Vol 26 (1) ◽

pp. 50-57 ◽

Cited By ~ 6

Author(s):

Marcela S. Salvarrey ◽

Juan José Cazzulo

Keyword(s):

Salt Concentration ◽

Malic Enzyme ◽

Mixed Type ◽

The Other ◽

Inhibition Kinetics ◽

Moderate Halophile ◽

Maximal Activation ◽

Regulatory Properties ◽

Better Than ◽

Mixed Type Inhibitor

NADP-specific malic enzyme (EC 1.1.1.40) has been purified about 160-fold from the moderate halophile Vibrio costicola. The enzyme has a molecular weight of about 120 000. The purified enzyme was unstable in dilute solutions but could be stabilised by NaCl or glycerol. NH4Cl or KCl caused maximal activation at 0.1 M, but higher concentrations were inhibitory. NaCl did not activate and was instead a mixed-type inhibitor towards NH4Cl or KCl. The salt concentration affected the kinetic parameters of the reaction. The apparent Km for L-malate reached a minimal value at about 0.1 M salt; the value for NADP, on the other hand, increased continuously with the salt concentration. The reaction also required a divalent cation activator, Mn2+ being better than Co2+ or Mg2+. NADH was a mixed-type inhibitor towards both substrates, whereas oxaloacetate was strictly competitive towards L-malate and non-competitive towards NADP. The inhibition kinetics were sigmoidal for NADH and hyperbolic for oxaloacetate. The malic enzyme from V. costicola was similar to those of a marine Pseudomonas and Halobacterium cutirubrum in kinetic and regulatory properties but showed a response to salts intermediate between those of the latter enzymes.

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