scholarly journals Substrate Kinetics of the Plant Mitochondrial Alternative Oxidase and the Effects of Pyruvate

1997 ◽  
Vol 115 (3) ◽  
pp. 1145-1153 ◽  
Author(s):  
MHN. Hoefnagel ◽  
P. R. Rich ◽  
Q. Zhang ◽  
J. T. Wiskich
Keyword(s):  
Alternative Oxidase ◽  
Kinetics Of ◽  
Substrate Kinetics

scholarly journals Substrate kinetics of the alternative oxidase of Neurospora crassa

1980 ◽  
Vol 186 (3) ◽  
pp. 1009-1011 ◽  
Author(s):  
J Vanderleyden ◽  
C Peeters ◽  
H Verachtert ◽  
H Bertrand
Keyword(s):  
Neurospora Crassa ◽  
Oxidase Activity ◽  
Alternative Oxidase ◽  
Submitochondrial Particles ◽  
Succinate Oxidation ◽  
Complex Ii ◽  
Ubiquinone Oxidoreductase ◽  
Kinetics Of ◽  
Substrate Kinetics

The kinetics of the succinate oxidation by cyanide-sensitive and cyanide-insensitive submitochondrial particles of Neurospora crassa cells suggest that both respiratory pathways use the same complex II. This is confirmed by comparing the kinetics of the reductase activities of the isolated succinate-ubiquinone oxidoreductase (complex II) of cyanide-sensitive and cyanide-insensitive cells respectively. No alternative-oxidase activity was found to be associated with the isolated complex II of cyanide-insensitive cells.

Substrate kinetics of DMSP-lyases in axenic cultures and mesocosm populations of Emiliania huxleyi

2007 ◽  
Vol 69 (3) ◽  
pp. 352-359 ◽  
Author(s):  
Michael Steinke ◽  
Claire Evans ◽  
Gareth A. Lee ◽  
Gill Malin
Keyword(s):  
Emiliania Huxleyi ◽  
Axenic Cultures ◽  
Kinetics Of ◽  
Substrate Kinetics

Comparative synthetic substrate kinetics of porcine acrosin and porcine β-trypsin

1979 ◽  
Vol 10 (3) ◽  
pp. 247-249 ◽  
Author(s):  
John D. Paulson ◽  
Richard F. Parrish ◽  
Kknnkth L. Polakoski
Keyword(s):  
Synthetic Substrate ◽  
Kinetics Of ◽  
Substrate Kinetics

scholarly journals Structure of the Zymomonas mobilis respiratory chain: oxygen affinity of electron transport and the role of cytochrome c peroxidase

Microbiology ◽  
2014 ◽  
Vol 160 (9) ◽  
pp. 2045-2052 ◽  
Author(s):  
Elina Balodite ◽  
Inese Strazdina ◽  
Nina Galinina ◽  
Samantha McLean ◽  
Reinis Rutkis ◽  
...  
Keyword(s):  
Electron Transport ◽  
Respiratory Chain ◽  
Peroxidase Activity ◽  
Zymomonas Mobilis ◽  
Alternative Oxidase ◽  
Oxygen Affinity ◽  
Aerobic Growth ◽  
Nadh Peroxidase ◽  
Kinetics Of

The genome of the ethanol-producing bacterium Zymomonas mobilis encodes a bd-type terminal oxidase, cytochrome bc 1 complex and several c-type cytochromes, yet lacks sequences homologous to any of the known bacterial cytochrome c oxidase genes. Recently, it was suggested that a putative respiratory cytochrome c peroxidase, receiving electrons from the cytochrome bc 1 complex via cytochrome c 552, might function as a peroxidase and/or an alternative oxidase. The present study was designed to test this hypothesis, by construction of a cytochrome c peroxidase mutant (Zm6-perC), and comparison of its properties with those of a mutant defective in the cytochrome b subunit of the bc 1 complex (Zm6-cytB). Disruption of the cytochrome c peroxidase gene (ZZ60192) caused a decrease of the membrane NADH peroxidase activity, impaired the resistance of growing culture to exogenous hydrogen peroxide and hampered aerobic growth. However, this mutation did not affect the activity or oxygen affinity of the respiratory chain, or the kinetics of cytochrome d reduction. Furthermore, the peroxide resistance and membrane NADH peroxidase activity of strain Zm6-cytB had not decreased, but both the oxygen affinity of electron transport and the kinetics of cytochrome d reduction were affected. It is therefore concluded that the cytochrome c peroxidase does not terminate the cytochrome bc 1 branch of Z. mobilis, and that it is functioning as a quinol peroxidase.

Expression and kinetics of the mitochondrial alternative oxidase in nitrogen-fixing nodules of soybean roots

1997 ◽  
Vol 20 (10) ◽  
pp. 1273-1282 ◽  
Author(s):  
A. H. MILLAR ◽  
P. M. FINNEGAN ◽  
J. WHELAN ◽  
J. J. DREVON ◽  
D. A. DAY
Keyword(s):  
Alternative Oxidase ◽  
Nitrogen Fixing ◽  
Soybean Roots ◽  
Kinetics Of

scholarly journals Comparison of the Kinetic Parameters of Alternative Oxidases From Trypanosoma brucei and Arabidopsis thaliana—A Tale of Two Cavities

2021 ◽  
Vol 12 ◽  
Author(s):  
Fei Xu ◽  
Alice C. Copsey ◽  
Luke Young ◽  
Mario R. O. Barsottini ◽  
Mary S. Albury ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Kinetic Parameters ◽  
Trypanosoma Brucei ◽  
Alternative Oxidase ◽  
General Structure ◽  
Oxygen Affinity ◽  
Catalytic Efficiency ◽  
Hydrophobic Cavity ◽  
Keto Acids ◽  
Kinetics Of

The alternative oxidase (AOX) is widespread in plants, fungi, and some protozoa. While the general structure of the AOX remains consistent, its overall activity, sources of kinetic activation and their sensitivity to inhibitors varies between species. In this study, the recombinant Trypanosoma brucei AOX (rTAO) and Arabidopsis thaliana AOX1A (rAtAOX1A) were expressed in the Escherichia coli ΔhemA mutant FN102, and the kinetic parameters of purified AOXs were compared. Results showed that rTAO possessed the highest Vmax and Km for quinol-1, while much lower Vmax and Km were observed in the rAtAOX1A. The catalytic efficiency (kcat/Km) of rTAO was higher than that of rAtAOX1A. The rTAO also displayed a higher oxygen affinity compared to rAtAOX1A. It should be noted that rAtAOX1a was sensitive to α-keto acids while rTAO was not. Nevertheless, only pyruvate and glyoxylate can fully activate Arabidopsis AOX. In addition, rTAO and rAtAOX1A showed different sensitivity to AOX inhibitors, with ascofuranone (AF) being the best inhibitor against rTAO, while colletochlorin B (CB) appeared to be the most effective inhibitor against rAtAOX1A. Octylgallate (OG) and salicylhydroxamic acid (SHAM) are less effective than the other inhibitors against protist and plant AOX. A Caver analysis indicated that the rTAO and rAtAOX1A differ with respect to the mixture of polar residues lining the hydrophobic cavity, which may account for the observed difference in kinetic and inhibitor sensitivities. The data obtained in this study are not only beneficial for our understanding of the variation in the kinetics of AOX within protozoa and plants but also contribute to the guidance for the future development of phytopathogenic fungicides.

scholarly journals Growth Kinetics of Suspended Microbial Cells: From Single-Substrate-Controlled Growth to Mixed-Substrate Kinetics

1998 ◽  
Vol 62 (3) ◽  
pp. 646-666 ◽  
Author(s):  
Karin Kovárová-Kovar ◽  
Thomas Egli
Keyword(s):  
Growth Kinetics ◽  
Kinetic Data ◽  
Carbon Sources ◽  
Microbial Cells ◽  
Mixed Substrate ◽  
Single Substrate ◽  
Pure Cultures ◽  
Defined Culture ◽  
Kinetics Of ◽  
Substrate Kinetics

SUMMARY Growth kinetics, i.e., the relationship between specific growth rate and the concentration of a substrate, is one of the basic tools in microbiology. However, despite more than half a century of research, many fundamental questions about the validity and application of growth kinetics as observed in the laboratory to environmental growth conditions are still unanswered. For pure cultures growing with single substrates, enormous inconsistencies exist in the growth kinetic data reported. The low quality of experimental data has so far hampered the comparison and validation of the different growth models proposed, and only recently have data collected from nutrient-controlled chemostat cultures allowed us to compare different kinetic models on a statistical basis. The problems are mainly due to (i) the analytical difficulty in measuring substrates at growth-controlling concentrations and (ii) the fact that during a kinetic experiment, particularly in batch systems, microorganisms alter their kinetic properties because of adaptation to the changing environment. For example, for Escherichia coli growing with glucose, a physiological long-term adaptation results in a change in KS for glucose from some 5 mg liter−1 to ca. 30 μg liter−1. The data suggest that a dilemma exists, namely, that either “intrinsic” KS (under substrate-controlled conditions in chemostat culture) or μmax (under substrate-excess conditions in batch culture) can be measured but both cannot be determined at the same time. The above-described conventional growth kinetics derived from single-substrate-controlled laboratory experiments have invariably been used for describing both growth and substrate utilization in ecosystems. However, in nature, microbial cells are exposed to a wide spectrum of potential substrates, many of which they utilize simultaneously (in particular carbon sources). The kinetic data available to date for growth of pure cultures in carbon-controlled continuous culture with defined mixtures of two or more carbon sources (including pollutants) clearly demonstrate that simultaneous utilization results in lowered residual steady-state concentrations of all substrates. This should result in a competitive advantage of a cell capable of mixed-substrate growth because it can grow much faster at low substrate concentrations than one would expect from single-substrate kinetics. Additionally, the relevance of the kinetic principles obtained from defined culture systems with single, mixed, or multicomponent substrates to the kinetics of pollutant degradation as it occurs in the presence of alternative carbon sources in complex environmental systems is discussed. The presented overview indicates that many of the environmentally relevant apects in growth kinetics are still waiting to be discovered, established, and exploited.

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