googling "dityrosine" suggests thaey can be formed by osidation by Cu or Ni ions.
In structures of cytochrome oxidase, Tyrosine forms a covalent bond
from the same meta carbon to NE2 of a histidine. see Fig 1 of:
http://www.sciencemag.org/content/280/5370/1723.long
And histidine is ligating a Cu.
It is believed to be functionally relevant.
James Stroud wrote:
> The hydroxyls were on the wrong carbons in the previous picture I sent. These are correct.
>
> James
>
>
> On Jul 11, 2012, at 1:37 PM, Lukacs, Christine wrote:
>
>> Hi all-
>> I have a protein that crystallizes in I422, and diffracts well, between 1.3-1.7A.
>> Beautiful density, slightly higher final R-factors than you might expect at this
>> resolution (low to mid 20s). The density is all beautiful, except that I have this one
>> little clash, between a few atoms from a tyrosine and its symmetry mate. In this picture
>> I have it modeled as an Alanine and you can see the two tyrosine rings interlocking; and
>> there is clearly no alternate conformation.
>> <image003.png>
>> Since it is not near my site of interest, I have been pretty much ignoring it, going
>> through refinement with it as an alanine, then changing it at the very end to a tyrosine
>> and just minimizing B-s, no positional. Now that I plan to publish a bunch of these, I
>> should probably figure out what is really going on. Any insights?
>> Thanks
>> Christine
>> *Christine Lukacs*
>> Roche
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