biochemistry question

[obiwan]

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is tyrosinase the same thing as tyrosine hydroxylase?

 

[BrisketAttack]

no. tyrosinase does tyro --> melanin
tyrosine hydroxylase does tyro --> dopa

 

[TerpMD]

no. tyrosinase does tyro --> melanin
tyrosine hydroxylase does tyro --> dopa

I'm confused about this too bc I thought that dopa was an intermediate for tyrosine synthesis. So if you have tyrosinase def, is it a direct prob with tyro-->mel? Trying to look this up has only caused me more confusion!

 

[obiwan]

FA has melanin branching off from DOPA which is formed from tyrosine via tyrosine hydroxylase so unless melanin is supposed to come off from tyrosine directly?

 

[osli]

FA is correct:

Tyrosine --(tyrosine hydroxylase)--> DOPA --(tyrosinase)--> dopaquinone ----------> melanin(s)

So from DOPA via DOPA decarboxylase you get dopamine, and also from DOPA via tyrosinase you get dopaquinone which leads to melanin synthesis. You don't want to know the whole chain.

I think.

 

[LUBDUBB]

FA is correct:

Tyrosine --(tyrosine hydroxylase)--> DOPA --(tyrosinase)--> dopaquinone ----------> melanin(s)

So from DOPA via DOPA decarboxylase you get dopamine, and also from DOPA via tyrosinase you get dopaquinone which leads to melanin synthesis. You don't want to know the whole chain.

I think.

Tyrosine --(tyrosine hydroxylase)---> L-dopa --> catecholamine synthesis

Tyrosine --(tyrosinase)--->L-dopa -----(tyrosinase again) -->Dopaquinone---> --> Melanin.

Note that there two ways to get L-dopa, one route is used for melanin synthesis and the other for catecholamine synthesis.

Side note: studies in mice have shown that under circumstances where Tyrosine hydroxylase is deficient, Tyrosinase may provide a compensatory pathway to synthesizing catecholamines. 👍