Reductase-catalyzed tetrahydrobiopterin regeneration alleviates the anti-competitive inhibition of tyrosine hydroxylation by 7,8-dihydrobiopterin

2021 ◽  
Author(s):  
Yinbiao Xu ◽  
Youran Li ◽  
Leyun Li ◽  
Liang Zhang ◽  
Zhongyang Ding ◽  
...  
Keyword(s):  
Tyrosine Hydroxylase ◽  
Competitive Inhibition ◽  
Tyrosine Hydroxylation

l-Tyrosine hydroxylation by tyrosine hydroxylase is a significant reaction for preparing many nutraceutical and pharmaceutical chemicals.

Determinants of cardiac tyrosine hydroxylase activity during exercise-induced sympathetic activation in humans

1998 ◽  
Vol 274 (3) ◽  
pp. R626-R634 ◽  
Author(s):  
Graeme Eisenhofer ◽  
Bengt Rundqvist ◽  
Peter Friberg
Keyword(s):  
Tyrosine Hydroxylase ◽  
Plasma Concentrations ◽  
Sympathetic Nerves ◽  
Relative Increase ◽  
Sympathetic Activation ◽  
Storage Vesicles ◽  
Extended Range ◽  
Tyrosine Hydroxylation ◽  
Exercise Induced ◽  
Venous Plasma

This study assessed whether the mechanisms regulating cardiac norepinephrine (NE) synthesis with changes in NE release are influenced by functions of sympathetic nerves affecting transmitter turnover independently of transmitter release. Differences in arterial and coronary venous plasma concentrations of NE and its metabolites and of dihydroxyphenylalanine (DOPA), the immediate product of tyrosine hydroxylase (TH), were examined before and during cycling exercise. Relative increases during exercise in cardiac tyrosine hydroxylation (as reflected by the %increase in cardiac DOPA spillover) matched closely corresponding increases in NE turnover, but were much lower than increases in NE release. The much larger relative increases in release than turnover of NE were largely attributable to the extensive contribution to transmitter turnover from intraneuronal metabolism of NE leaking from storage vesicles. This contribution remains unchanged during sympathetic activation so that the relative increase in NE turnover is much smaller than that in exocytotic release of NE. To replenish the NE lost from stores during sympathetic activation, TH activity need increase only in proportion to the smaller increase in turnover rather than the larger relative increase in release. The ability to “gear down” increases in tyrosine hydroxylation relative to increases in NE release provides sympathetic nerves the capacity for a more extended range of sustainable release rates than otherwise possible.

Influence of 7,8 Dihydroneopterin and Hyperoxia on Neurite Growth and Tyrosine Hydroxylase Activity of PC 12 Cells

Pteridines ◽  
2002 ◽  
Vol 13 (3) ◽  
pp. 94-99
Author(s):  
Karoline Vrecko ◽  
Gilbert Reibnegger
Keyword(s):  
Tyrosine Hydroxylase ◽  
Hydroxyl Radicals ◽  
Incubation Medium ◽  
Neurite Growth ◽  
Radical Formation ◽  
Iron Ions ◽  
Hydroxylase Activity ◽  
Pc 12 Cells ◽  
Tyrosine Hydroxylase Activity ◽  
Tyrosine Hydroxylation

Abstract The influence of dihydroneopterin on tyrosine hydroxylase activity in PC 12 cells was investigated under normoxic and hyperoxic conditions, and with or without iron ions in the incubation medium. Low dihydroneopterin concentrations as well as hyperoxia increase tyrosine hydroxylase activity. Due to a too vigorous radical formation, high dihydroneopterin concentrations lead to a decrease of tyrosine hydroxylation in normoxic state and even more strongly in hyperoxic state. Similar depression of tyrosine hydroxylase activity was seen after addition of iron ions, which can form hydroxyl radicals by a Fenton type reaction. As higher iron concentrations in combination with dihydroneopterin do not suppress tyrosine hydroxylase activity completely, we conclude that dihydroneopterin and iron ions react with each other resulting in neutralisation of their effects. In conclusion, 7,8 dihydroneopterin can modulate tyrosine hydroxylase activity and its effects are dependent on concentration of oxygen as well as presence or absence of iron ions.

scholarly journals Effects of ovariectomy and oestradiol-17beta replacement on brain tyrosine hydroxylase in the catfish Heteropneustes fossilis: changes in in vivo activity and kinetic parameters

2002 ◽  
Vol 175 (2) ◽  
pp. 329-342 ◽  
Author(s):  
R Chaube ◽  
KP Joy
Keyword(s):  
Body Weight ◽  
Tyrosine Hydroxylase ◽  
Brain Regions ◽  
Inhibitory Effect ◽  
Heteropneustes Fossilis ◽  
Gonadotrophin Secretion ◽  
Tyrosine Hydroxylation ◽  
Brain Tyrosine Hydroxylase ◽  
Biphasic Responses

In Heteropneustes fossilis, ovariectomy inhibited in vivo brain (hypothalamus-pituitary, telencephalon and medulla oblongata) tyrosine hydroxylase (TH) activity with significant effects in weeks 2, 3, 4 and 5 of the gonadal resting phase and in weeks 3, 4 and 5 of the prespawning phase (P<0.05, Tukey's test). Oestradiol-17beta (OE(2)) replacement in 3-week ovariectomised fish produced biphasic responses in both seasons; the low dosages of 0.05 and 0.5 micro g/g body weight (BW) elevated TH activity, whereas the high dosages of 1.0 and 2.0 micro g/g BW decreased it. The magnitude of the inhibition was higher in the resting phase than in the prespawning phase. The inhibitory effect of ovariectomy may be produced by elevating the apparent K(m) values (decreased affinity) of the enzyme for both L-tyrosine (substrate) and dimethyltetrahydropteridine (cofactor) and consequently decreasing the V(max). Significant changes (P<0.05) in both these parameters were noticed but showed minor differences with regard to the length of ovariectomy, season or brain regions. The biphasic effects of OE(2) replacement on TH activity seemed to be produced by differential effects on apparent K(m) and V(max). The stimulatory effect of the low dosages of OE(2) coincides with a decrease in the apparent K(m) values (increased affinity) for both substrate and cofactor and an increase in the V(max) of the enzyme. The inhibitory effect of the high dosages of OE(2) correlated with an increase in the apparent K(m) values (decreased affinity) for both substrate and cofactor, and a decrease in the V(max) compared with the lower dosage groups. The results strongly suggested that OE(2) can modulate brain catecholaminergic activity at the level of tyrosine hydroxylation which, in turn, may alter gonadotrophin secretion. OE(2) may elicit biphasic effects by differentially altering the enzyme affinity towards the substrate and cofactor.

scholarly journals Expression of the Tyrosine Hydroxylase Gene from Rat Leads to Oxidative Stress in Potato Plants

Antioxidants ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 717 ◽  
Author(s):  
Kamil Kostyn ◽  
Aleksandra Boba ◽  
Anna Kostyn ◽  
Bartosz Kozak ◽  
Michał Starzycki ◽  
...  
Keyword(s):  
Tyrosine Hydroxylase ◽  
Stress Condition ◽  
Oxygen Species ◽  
Tyrosine Hydroxylase Gene ◽  
Potato Plants ◽  
Hydroxylase Gene ◽  
Animal System ◽  
Reactive Oxygen Species Content ◽  
Tyrosine Hydroxylation ◽  
Resistance To Infection

Catecholamines are biogenic aromatic amines common among both animals and plants. In animals, they are synthesized via tyrosine hydroxylation, while both hydroxylation or decarboxylation of tyrosine are possible in plants, depending on the species, though no tyrosine hydroxylase—a counterpart of the animal enzyme—has been identified yet. It is known that in potato plants, it is the decarboxylation of tyrosine that leads to catecholamine production. In this paper, we present the effects of the induction of an alternative route of catecholamine production by introducing the tyrosine hydroxylase gene from rat. We demonstrate that an animal system can be used by the plant. However, it does not function to synthesize catecholamines. Instead, it leads to elevated reactive oxygen species content and a constant stress condition in the plant, which responds with elevated antioxidant levels and improved resistance to infection.

Mutation of Serine 395 of Tyrosine Hydroxylase Decouples Oxygen−Oxygen Bond Cleavage and Tyrosine Hydroxylation†

Biochemistry ◽  
2000 ◽  
Vol 39 (14) ◽  
pp. 4174-4181 ◽  
Author(s):  
Holly R. Ellis ◽  
S. Colette Daubner ◽  
Paul F. Fitzpatrick
Keyword(s):  
Tyrosine Hydroxylase ◽  
Bond Cleavage ◽  
Oxygen Oxygen ◽  
Tyrosine Hydroxylation ◽  
Oxygen Bond

Studies on phenylalanine and tyrosine hydroxylation by rat brain tyrosine hydroxylase

1976 ◽  
Vol 445 (3) ◽  
pp. 567-578 ◽  
Author(s):  
Ira Katz ◽  
Tom Lloyd ◽  
Seymour Kaufman
Keyword(s):  
Tyrosine Hydroxylase ◽  
Rat Brain ◽  
Tyrosine Hydroxylation ◽  
Brain Tyrosine Hydroxylase

scholarly journals Expression of tyrosine hydroxylase gene from rat leads to oxidative stress in potato plants

2020 ◽  
Author(s):  
Kamil Kostyn ◽  
Aleksandra Boba ◽  
Anna Kostyn ◽  
Michał Starzycki ◽  
Jan Szopa ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Tyrosine Hydroxylase ◽  
Antioxidant Response ◽  
Tyrosine Hydroxylase Gene ◽  
Potato Plants ◽  
Hydroxylase Gene ◽  
Animal System ◽  
Reactive Oxygen Species Content ◽  
Tyrosine Hydroxylation ◽  
Resistance To Infection

AbstractCatecholamines are biogenic aromatic amines common among both animals and plants. In animals they are synthesized via tyrosine hydroxylation, while in plants, both hydroxylation or decarboxylation of tyrosine are possible, depending on the species, though no tyrosine hydroxylase – a counterpart of animal enzyme has been identified yet. It is known that in potato plants it is the decarboxylation of tyrosine that leads to catecholamine production. In this paper we present the effects of induction of an alternative route of catecholamine production by introducing tyrosine hydroxylase gene from rat. We demonstrate that an animal system can be used by the plant, however, it does not function to synthesize catecholamines. Instead it leads to elevated reactive oxygen species content and constant stress condition to the plant which responds with elevated antioxidant level and further with improved resistance to infection.One sentence summaryIntroduction of rat tyrosine hydroxylase gene to potato disturbs catecholamine synthesis, causes oxidative stress and activates antioxidant response.

Colocalization of tyrosine hydroxylase and GAD65 mRNA in mesostriatal neurons

2001 ◽  
Vol 13 (1) ◽  
pp. 57-67 ◽  
Author(s):  
Tomas Gonzalez-Hernandez ◽  
Pedro Barroso-Chinea ◽  
Abraham Acevedo ◽  
Eduardo Salido ◽  
Manuel Rodriguez
Keyword(s):  
Tyrosine Hydroxylase
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