scholarly journals The Structure and Competitive Substrate Inhibition of Dihydrofolate Reductase fromEnterococcus faecalisReveal Restrictions to Cofactor Docking

Biochemistry ◽  
2014 ◽  
Vol 53 (7) ◽  
pp. 1228-1238 ◽  
Author(s):  
Christina R. Bourne ◽  
Nancy Wakeham ◽  
Nicole Webb ◽  
Baskar Nammalwar ◽  
Richard A. Bunce ◽  
...  
Keyword(s):  
Dihydrofolate Reductase ◽  
Substrate Inhibition ◽  
Competitive Substrate

Gamma-glutamyltransferase: Substrate inhibition, kinetic mechanism, and assay conditions.

1976 ◽  
Vol 22 (4) ◽  
pp. 417-421 ◽  
Author(s):  
J H Stromme ◽  
L Theodorsen
Keyword(s):  
Clinical Chemistry ◽  
Substrate Inhibition ◽  
Kinetic Mechanism ◽  
Reaction Conditions ◽  
Gamma Glutamyltransferase ◽  
Gamma Glutamyl ◽  
Dead End ◽  
Ping Pong ◽  
Competitive Substrate ◽  
Assay Conditions

Abstract Gamma-glutamyltransferase activity in serum is shown to be competitively inhibited by the two substrates gamma-glutamyl-4-nitroanilide and glycylglycine. Awareness of this is of importance when one is choosing final reaction conditions for the assay of the enzyme. Gamma-glutamyltransferase probably acts by a "ping-pong bi-bi" kinetic mechanism, which fits with the double competitive substrate inhibition demonstrated. The product, 4-nitro-aniline, appears to be an uncompetitive dead-end inhibitor of both substrates. Various amino acids, particularly glycine and L-alanine, inhibit the enzyme. Their inhibition patterns are uncompetitive with glycylglycine and competitive with gamma-glutamyl-4-nitroanilide. On the basis of the present and other studies, the Scandinavian Society for Clinical Chemistry and Clinical Physiology is going to recommend for routine use a gamma-glutamyltransferase method in which the final concentrations of gamma-glutamyl-4-nitroanilide and glycylglycine are 4 and 75 mmol/liter, respectively.

Competitive substrate inhibition of amyloglucosidase fromRhizopussp. by vanillin and curcumin

2006 ◽  
Vol 24 (4) ◽  
pp. 299-305 ◽  
Author(s):  
Ramaiah Sivakumar ◽  
Giriyapura R. Vijayakumar ◽  
Balaraman Manohar ◽  
Soundar Divakar
Keyword(s):  
Substrate Inhibition ◽  
Competitive Substrate

Computational biotechnology: Prediction of competitive substrate inhibition of enzymes by buffer compounds with protein–ligand docking

2012 ◽  
Vol 161 (4) ◽  
pp. 391-401 ◽  
Author(s):  
Karen T. Schomburg ◽  
Inés Ardao ◽  
Katharina Götz ◽  
Fabian Rieckenberg ◽  
Andreas Liese ◽  
...  
Keyword(s):  
Substrate Inhibition ◽  
Ligand Docking ◽  
Competitive Substrate

scholarly journals Trypanosoma cruzi synthesizes proline via a Δ1-pyrroline-5-carboxylate reductase whose activity is fine-tuned by NADPH cytosolic pools

2020 ◽  
Vol 477 (10) ◽  
pp. 1827-1845
Author(s):  
Letícia Marchese ◽  
Karel Olavarria ◽  
Brian Suarez Mantilla ◽  
Carla Cristi Avila ◽  
Rodolpho Ornitiz Oliveira Souza ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Thermal Stresses ◽  
Substrate Inhibition ◽  
Inhibition Mechanism ◽  
Atp Production ◽  
Kinetic Inhibition ◽  
Redox Shuttle ◽  
High Concentrations ◽  
Competitive Substrate ◽  
Carboxylate Reductase

In Trypanosoma cruzi, the etiological agent of Chagas disease, the amino acid proline participates in processes related to T. cruzi survival and infection, such as ATP production, cell differentiation, host-cell invasion, and in protection against osmotic, nutritional, and thermal stresses and oxidative imbalance. However, little is known about proline biosynthesis in this parasite. Δ1-Pyrroline-5-carboxylate reductase (P5CR, EC 1.5.1.2) catalyzes the biosynthesis of proline from Δ1-pyrroline-5-carboxylate (P5C) with concomitant NADPH oxidation. Herein, we show that unlike other eukaryotes, T. cruzi biosynthesizes proline from P5C, which is produced exclusively from glutamate. We found that TcP5CR is an NADPH-dependent cytosolic enzyme with a Kmapp for P5C of 27.7 μM and with a higher expression in the insect-resident form of the parasite. High concentrations of the co-substrate NADPH partially inhibited TcP5CR activity, prompting us to analyze multiple kinetic inhibition models. The model that best explained the obtained data included a non-competitive substrate inhibition mechanism (Kiapp=45±0.7μM). Therefore, TcP5CR is a candidate as a regulatory factor of this pathway. Finally, we show that P5C can exit trypanosomatid mitochondria in conditions that do not compromise organelle integrity. These observations, together with previously reported results, lead us to propose that in T. cruzi TcP5CR participates in a redox shuttle between the mitochondria and the cytoplasm. In this model, cytoplasmic redox equivalents from NADPH pools are transferred to the mitochondria using proline as a reduced metabolite, and shuttling to fuel electrons to the respiratory chain through proline oxidation by its cognate dehydrogenase.

scholarly journals Purification and steady-state kinetics of adenosine 5′-pyrophosphate sulphurylase from baker's yeast

1977 ◽  
Vol 165 (1) ◽  
pp. 149-155 ◽  
Author(s):  
R G Nicholls
Keyword(s):  
Exchange Reaction ◽  
Initial Velocity ◽  
Isotope Exchange ◽  
Substrate Inhibition ◽  
Deae Cellulose ◽  
Product Inhibition ◽  
Steady State Kinetics ◽  
Ping Pong ◽  
Competitive Substrate ◽  
Kinetics Of

ADP sulphurylase (EC 2.7.7.5) was purified by chromatography on Sephadex G-200 and DEAE-cellulose. The enzyme was assayed by measuring the incorporation of [32P]Pi into ADP in the presence of the substrate for the reverse reaction, adenosine 5′-sulphatophosphate. In the concentration ranges investigated, by using initial-velocity, product-inhibition and isotope-exchange studies, the data were consistent with a Ping Pong reaction mechanism, with Km for adenosine 5′-sulphatophosphate of 1.20 +/- 0.08 mM and a Km for Pi of 4.95 +/- 0.15 mM. Competitive substrate inhibition by Pi (Ki = 11.7 +/- 0.3 mM) was found. ADP sulphurylase catalyses a sulphate-independent Pi-ADP exchange reaction, the kinetics of which are consistent with the kinetics of the overall reaction, inconsistent with the assay of Burnell & Anderson [(1973) Biochem. J. 133, 417-428], which is based on a sulphate-dependent Pi-ADP exchange reaction.

Competitive substrate inhibition in the histochemistry of cholinesterase activity in Alzheimer's disease

1990 ◽  
Vol 117 (1-2) ◽  
pp. 56-61 ◽  
Author(s):  
Christoph R. Schätz ◽  
Changiz Geula ◽  
Marsel Mesulam
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cholinesterase Activity ◽  
Substrate Inhibition ◽  
Competitive Substrate

Biodegradation Characteristics and Bioaugmentation Potential of an Efficient O-Cresol-Degrading Strain Isolated from Petrochemical Sewage Treatment Plant

2013 ◽  
Vol 726-731 ◽  
pp. 264-268
Author(s):  
Jia Bao Yan ◽  
Long Long Xu ◽  
Xin Wei
Keyword(s):  
Degradation Kinetics ◽  
Substrate Inhibition ◽  
Sewage Treatment ◽  
Water Environment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Refinery Wastewater ◽  
High Concentration ◽  
16S Rdna Sequence Analysis ◽  
Competitive Substrate

O-cresol and its isomers are one of the major pollutants to water environment. In this study, a highly effective o-cresol-degradation strain was isolated from the activated sludge of a petrochemical sewage treatment. Based on its morphology, physiological characteristics and 16S rDNA sequence analysis, it was identified as Pseudomonas sp. The optimal operating temperature, initial pH and rotary shaker speed for the strain to degrade o-cresol were experimentally determined to be 30°C,pH 6.5~8.0 and 150~200 rpm, respectively. Substrate scope experiment showed that the strain can degrade o-cresols other isomers and phenol. The degradation kinetics of the strain can be described by competitive substrate inhibition model with a maximum specific degradation rate of 0.055h-1. Furthermore, the bioaugmentation of the strain in the refinery wastewater to degrade o-cresol was investigated. The result showed that the strain is able to survive in refinery wastewater with high concentration of o-cresol and remove it efficiently.

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