tyrosinase vs tyrosine hydroxylase

[ssa915]

Having trouble differentiating tyrosinase vs tyrosine hydroxylase.

1. When converting tyrosine into DOPA, does it use tyrosinase or tyrosine hydroxylase?

2. When making melanin, is the pathway:

Tyrosine --> (via tyrosinase) --> DOPA --> Melanin

OR is it...

Tyrosine --> (via tyrosine hydroxylase) --> DOPA --> (via tyrosinase) --> Melanin

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[bodonid]

tyrosinase catalyzes both reactions. They are probably not in the same tissue together, either, right?

 

[Tristy]

Having trouble differentiating tyrosinase vs tyrosine hydroxylase.

1. When converting tyrosine into DOPA, does it use tyrosinase or tyrosine hydroxylase?

2. When making melanin, is the pathway:

Tyrosine --> (via tyrosinase) --> DOPA --> Melanin

OR is it...

Tyrosine --> (via tyrosine hydroxylase) --> DOPA --> (via tyrosinase) --> Melanin

According to Lippincott, they are the same enzime (tyr hydroxylase and tyrosinase). And from what I read, yes, it is as you wrote it

Tyrosine --> (via tyrosine hydroxylase) --> DOPA --> (via tyrosinase, aka tyrosine hydroxylase) --> --> --> Melanin

Hope that helps

 

[jeesapeesa]

tyrosine --> DOPA --tyrosinase--> melanin
tyrosine --> tyrosine hydroxylase --> DOPA --> catecholamines

 

[Phloston]

Old thread, but I was Googling in order to find out the difference between tyrosinase and tyrosine hydroxylase, because I've seen them thrown around somewhat interchangeably for the longest time now (and then I finally flipped out because I needed conclusiveness), although I've been aware that the former is more tied into melanin synthesis. Anyway:

Tyrosine, via tyrosinase in melanosomes or tyrosine hydroxylase in adrenal chromaffin cells, --> L-Dopa. Then, in both cell-types, L-Dopa can be converted, via tyrosinase, into dopaquinone. Dopaquinone is then shuttled through three different melanin synthesis pathways, each yielding a different type of melanin with a resultant varying degree of photo-absorbance.

I retrieved the following image from: http://jn.nutrition.org/content/132/6/1646S.full. If you're curious, read the paragraph preceding the image in the article. It's basically what I just summarized above.

I'm actually surprised that I haven't encountered a single question on this difference across ~12,500 practice questions so far. It might not be the highest yield topic ever, but it's needless to say that I've seen much lower-yield crap floating around.

Cheers,

 

[JTster]

I was confused about the two enzymes as well but now I feel much better Thanks!

Old thread, but I was Googling in order to find out the difference between tyrosinase and tyrosine hydroxylase, because I've seen them thrown around somewhat interchangeably for the longest time now (and then I finally flipped out because I needed conclusiveness), although I've been aware that the former is more tied into melanin synthesis. Anyway:

Tyrosine, via tyrosinase in melanosomes or tyrosine hydroxylase in adrenal chromaffin cells, --> L-Dopa. Then, in both cell-types, L-Dopa can be converted, via tyrosinase, into dopaquinone. Dopaquinone is then shuttled through three different melanin synthesis pathways, each yielding a different type of melanin with a resultant varying degree of photo-absorbance.

I retrieved the following image from: http://jn.nutrition.org/content/132/6/1646S.full. If you're curious, read the paragraph preceding the image in the article. It's basically what I just summarized above.

I'm actually surprised that I haven't encountered a single question on this difference across ~12,500 practice questions so far. It might not be the highest yield topic ever, but it's needless to say that I've seen much lower-yield crap floating around.

Cheers,

 

[Lyme cartell]

I know this is an old thread but perhaps someone might help. T. Gondi infection appears to modify tyrosine hydroxylase (TH), the rate-limiting enzyme for dopamine synthesis. Antibodies specific to the parasite-encoded TH have been found in intracellular tissue cysts in infected rat tissue. This makes brakes come off dopamine production in these infections.

Can one assume that parasite-encoded tyrosine hydroxylase (TH) is identical to naturally produced TH and therefore it also would be disrupted? What would that do to melanin production with regard to stepwise production as above?