Fe & tyrosine hydroxylase

Michael L. Kirby mkirby at vt.edu
Wed Oct 25 21:41:44 EST 1995

jomartin at crab.rutgers.edu (Joseph V. Martin) wrote:
> I had previously understood that Fe2+ was a cofactor for tyrosine
> hydroxylase.  However, I notice that more recent reviews (Weiner &
> Molinoff in Basic Neurochemistry) don't mention Fe with regard to
> TH. Was my earlier understanding incorrect?
> Thanks for your help!

Yes, you are correct.  Since TH is a mixed function oxdiase (P450),
iron is a requirement for oxygen binding by the cytochrome (recall,
the iron is electrostatically suspended in the center of the structure).
For awhile, the discovery of P450s was a really hot research topic,
not that it isn't now, but our understanding of the enzymes
was rather new (probably about the time those texts you are
referring to were written).  Nowadays, if an enzyme is classified
as a P450, you know it uses Fe2+, and more emphasis is placed
on explaining energy requirements (e.g., NADPH, tetrahydro folate)
and allosteric modification/regulation of function.


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