Subject: Why are tyrosines so important in binding iron in transferrins

I have been looking at a number of transferrin molecules and related proteins
from bacteria and have noticed that two tyrosines are always involved in binding
to the iron molecule while the other amino acids utilized vary. I am wondering
why two tyrosines are always used when it appears that other amino acids could
be used. Any suggestions would help I became curious when I noticed this common
theme.

Re: Why are tyrosines so important in binding iron in transferrins