Haemoglobin question

[Nick Fisher]

I have recently isolated a water soluble b-type haemoprotein from
Brassica napa which I believe to be cytochrome b3. N-terminal sequencing
of this protein reveals an FQKV motif. The aromatic-Q-K-aromatic motif
is apparently extremely well conserved around position c.130 in the haemoglobin 
beta chain (owl database search with the gcg software package). I would
appreciate any information as to the structural role (if any) of the
arm-Q-K-arm motif in Hb.

thanks in advance

Nick Fisher
Dept. Biochemisty
Cambridge University
UK