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Difference between revisions of "Rostrup M 2008 Amino Acids"

From Bioblast
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|journal=Amino Acids
|journal=Amino Acids
|mipnetlab=AT_Innsbruck_GnaigerE
|mipnetlab=AT_Innsbruck_GnaigerE
|abstract=The effects of dioxygen on tyrosine hydroxylase (TH) activity
|abstract=The effects of dioxygen on tyrosine hydroxylase (TH) activity was studied, measuring the formation of DOPA from tyrosine, 3H<sub>2</sub>O from 3,5-3H-tyrosine, or by direct oxygraphic determination of oxygen consumption. A high enzyme activity was observed during the initial 1–2 min of the reactions, followed by a decline in activity, possibly related to a turnover dependent substoichiometrical oxidation of enzyme bound Fe(II) to the inactive Fe(III) state. During the initial reaction phase, apparent Km-values of 29–45 Β΅M for dioxygen were determined for all human TH isoforms, i.e. 2–40 times higher than previously reported for TH isolated from animal tissues. After 8 min incubation, the Km (O<sub>2</sub>)-values had declined to an average of 20 Β± 4 Β΅M. Thus, TH activity may be severely limited by oxygen availability even atmoderate hypoxic conditions, and the enzyme is rapidly and turnover dependent inactivated at the experimental conditions commonly employed to measure in vitro activities.
was studied, measuring the formation of DOPA from tyrosine, 3H2O from
|keywords=Catecholamines, Human, Hypoxia, Oxygen, Tyrosine hydroxylase
3,5-3H-tyrosine, or by direct oxygraphic determination of oxygen consumption.
A high enzyme activity was observed during the initial 1–2 min
of the reactions, followed by a decline in activity, possibly related to a
turnover dependent substoichiometrical oxidation of enzyme bound Fe(II)
to the inactive Fe(III) state. During the initial reaction phase, apparent
Km-values of 29–45 Β΅M for dioxygen were determined for all human TH
isoforms, i.e. 2–40 times higher than previously reported for TH isolated
from animal tissues. After 8 min incubation, the Km (O2)-values had declined
to an average of 20 Β± 4 Β΅M. Thus, TH activity may be severely
limited by oxygen availability even atmoderate hypoxic conditions, and the
enzyme is rapidly and turnover dependent inactivated at the experimental
conditions commonly employed to measure in vitro activities.
|keywords=Catecholamines – Human – Hypoxia – Oxygen – Tyrosine hydroxylase
|info=[http://www.ncbi.nlm.nih.gov/pubmed/17520326 PMID: 17520326]
|info=[http://www.ncbi.nlm.nih.gov/pubmed/17520326 PMID: 17520326]
}}
}}

Revision as of 14:13, 15 September 2010

Publications in the MiPMap
Rostrup M, Fossbakk A, Hauge A, Kleppe R, Gnaiger E, Haavik J (2008) Oxygen dependence of tyrosine hydroxylase. Amino Acids 34: 455-464.

Β» PMID: 17520326

Rostrup M, Fossbakk A, Hauge A, Kleppe R, Gnaiger E, Haavik J (2008) Amino Acids

Abstract: The effects of dioxygen on tyrosine hydroxylase (TH) activity was studied, measuring the formation of DOPA from tyrosine, 3H2O from 3,5-3H-tyrosine, or by direct oxygraphic determination of oxygen consumption. A high enzyme activity was observed during the initial 1–2 min of the reactions, followed by a decline in activity, possibly related to a turnover dependent substoichiometrical oxidation of enzyme bound Fe(II) to the inactive Fe(III) state. During the initial reaction phase, apparent Km-values of 29–45 Β΅M for dioxygen were determined for all human TH isoforms, i.e. 2–40 times higher than previously reported for TH isolated from animal tissues. After 8 min incubation, the Km (O2)-values had declined to an average of 20 Β± 4 Β΅M. Thus, TH activity may be severely limited by oxygen availability even atmoderate hypoxic conditions, and the enzyme is rapidly and turnover dependent inactivated at the experimental conditions commonly employed to measure in vitro activities. β€’ Keywords: Catecholamines, Human, Hypoxia, Oxygen, Tyrosine hydroxylase

β€’ O2k-Network Lab: AT_Innsbruck_GnaigerE


Labels:

Stress:Hypoxia  Organism: Human 

Preparation: Enzyme 



HRR: Oxygraph-2k