Step I tyrosinase vs tyrosine hydroxylase

ssa915 said:

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

Click to expand...

Phloston said:

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,

Click to expand...