Difference between revisions of "Rostrup M 2008 Amino Acids"
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{{Publication | {{Publication | ||
|title=Rostrup M, Fossbakk A, Hauge A, Kleppe R, Gnaiger E, Haavik J (2008) Oxygen dependence of tyrosine hydroxylase. Amino Acids 34: 455- | |title=Rostrup M, Fossbakk A, Hauge A, Kleppe R, Gnaiger E, Haavik J (2008) Oxygen dependence of tyrosine hydroxylase. Amino Acids 34:455-64. | ||
|authors=Rostrup M, Fossbakk A, Hauge A, Kleppe R, Gnaiger | |info=[http://www.ncbi.nlm.nih.gov/pubmed/17520326 PMID: 17520326] | ||
|authors=Rostrup M, Fossbakk A, Hauge A, Kleppe R, Gnaiger Erich, Haavik J | |||
|year=2008 | |year=2008 | ||
|journal=Amino Acids | |journal=Amino Acids | ||
|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 µM 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 ± 4 µM. 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. | |||
|abstract=The effects of dioxygen on tyrosine hydroxylase (TH) activity | |keywords=Catecholamines, Human, Hypoxia, Oxygen, Tyrosine hydroxylase | ||
was studied, measuring the formation of DOPA from tyrosine, | |mipnetlab=AT Innsbruck Gnaiger E | ||
3,5-3H-tyrosine, or by direct oxygraphic determination of oxygen consumption. | |discipline=Biomedicine | ||
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 µM 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 ( | |||
to an average of 20 ± 4 µM. 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 | |||
| | |||
}} | }} | ||
{{Labeling | {{Labeling | ||
|area=Instruments;methods | |||
|organism=Human | |||
|preparations=Enzyme, Oxidase;biochemical oxidation | |||
|topics=Oxygen kinetics, Substrate | |||
|pathways=ROX | |||
|instruments=Oxygraph-2k | |instruments=Oxygraph-2k | ||
|discipline=Biomedicine | |discipline=Biomedicine | ||
}} | }} | ||
Latest revision as of 04:03, 23 November 2021
| Rostrup M, Fossbakk A, Hauge A, Kleppe R, Gnaiger E, Haavik J (2008) Oxygen dependence of tyrosine hydroxylase. Amino Acids 34:455-64. |
Rostrup M, Fossbakk A, Hauge A, Kleppe R, Gnaiger Erich, 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 µM 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 ± 4 µM. 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
• O2k-Network Lab: AT Innsbruck Gnaiger E
Labels: MiParea: Instruments;methods
Organism: Human
Preparation: Enzyme, Oxidase;biochemical oxidation
Regulation: Oxygen kinetics, Substrate
Pathway: ROX HRR: Oxygraph-2k
