scholarly journals Investigations on the Kinetic Mechanism of Octopine Dehydrogenase. 2. Location of the Rate-Limiting Step for Enzyme Turnover

1975 ◽  
Vol 59 (1) ◽  
pp. 185-191 ◽  
Author(s):  
Marie-Odile DOUBLET ◽  
Anna OLOMUCKI ◽  
Antonio BAICI ◽  
Pier Luigi LUISI
1989 ◽  
Vol 21 (4-5) ◽  
pp. 175-186 ◽  
Author(s):  
C. Y. Lin ◽  
T. Noike ◽  
H. Furumai ◽  
J. Matsumoto

Results obtained from experiments on two-phase anaerobic digestion using a high concentration of a volatile fatty acid (VFA) mixture were used to elucidate the kinetic mechanism of the methanogenesis process. The mixture consisted of the major intermediate products of anaerobic digestion, i.e., acetic acid (HAc), propionic acid (HPr) and butyric acid (HBu). The relationship between the rate of substrate utilization and substrate concentration in the digesters was in the form of a Michaelis-Menten equation. The rate-limiting step of the methanogenesis process, i.e., the conversion of HAc to methane, was speeded up in the digesters and this was proved kinetically. A method for determining kinetic constants for substrate-specific microorganisms was suggested. A simulation model for predicting the effluent substrate concentration was demonstrated. The effluent substrate concentration of an anaerobic digester fed by a multisubstrate was found to be simulatively predictable from its influent component substrates.


2015 ◽  
Vol 290 (13) ◽  
pp. 8656-8665 ◽  
Author(s):  
Somchart Maenpuen ◽  
Watcharee Amornwatcharapong ◽  
Pasupat Krasatong ◽  
Jeerus Sucharitakul ◽  
Bruce A. Palfey ◽  
...  

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lena A. K. Bögeholz ◽  
Evan Mercier ◽  
Wolfgang Wintermeyer ◽  
Marina V. Rodnina

AbstractSynthesis of bacterial proteins on the ribosome starts with a formylated methionine. Removal of the N-terminal formyl group is essential and is carried out by peptide deformylase (PDF). Deformylation occurs co-translationally, shortly after the nascent-chain emerges from the ribosomal exit tunnel, and is necessary to allow for further N-terminal processing. Here we describe the kinetic mechanism of deformylation by PDF of ribosome-bound nascent-chains and show that PDF binding to and dissociation from ribosomes is rapid, allowing for efficient scanning of formylated substrates in the cell. The rate-limiting step in the PDF mechanism is a conformational rearrangement of the nascent-chain that takes place after cleavage of the formyl group. Under conditions of ongoing translation, the nascent-chain is deformylated rapidly as soon as it becomes accessible to PDF. Following deformylation, the enzyme is slow in releasing the deformylated nascent-chain, thereby delaying further processing and potentially acting as an early chaperone that protects short nascent chains before they reach a length sufficient to recruit other protein biogenesis factors.


1978 ◽  
Vol 39 (02) ◽  
pp. 496-503 ◽  
Author(s):  
P A D’Amore ◽  
H B Hechtman ◽  
D Shepro

SummaryOrnithine decarboxylase (ODC) activity, the rate-limiting step in the synthesis of polyamines, can be demonstrated in cultured, bovine, aortic endothelial cells (EC). Serum, serotonin and thrombin produce a rise in ODC activity. The serotonin-induced ODC activity is significantly blocked by imipramine (10-5 M) or Lilly 11 0140 (10-6M). Preincubation of EC with these blockers together almost completely depresses the 5-HT-stimulated ODC activity. These observations suggest a manner by which platelets may maintain EC structural and metabolic soundness.


Diabetes ◽  
1993 ◽  
Vol 42 (2) ◽  
pp. 296-306 ◽  
Author(s):  
D. C. Bradley ◽  
R. A. Poulin ◽  
R. N. Bergman

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