I need any recommendations ...

[borovok ilya]

 Dear Netters,

I would like to ask you help me in seasrching any nice (possibly modern) 
review and other sources concerning a phenomenon of an iron binding by 
proteins. It's not very easy question.

My case: I am a genetist and at present deal with a genetical analysis of 
Isopenicillin N Synthase (IPNS) from Streptomyces. It is non heme enzyme and 
requires Fe(II) as a cofactor. We did make mutations which switch off an 
activity of this enzyme and found all potential ligands which involved in 
iron-binding to form an active site; the same ligands have been shown 
recently in Nature (22 June, 95) for another IPNS from Aspergillus nidulans 
by use of 3D structure. So far this 3D structure is not placed in PDB. We 
and they did show there are two histidines and one aspartic acid those are 
ligands of this kind of dioxygenases. But in our case the 'total', triple, 
mutant IPNS protein with  all switched off ligands did ... binds iron also 
very well. This unspecific (?) iron binding is same for both wild type 
protein and any mutant protein. This binding is very strong and an 
iron-IPNS-protein complex is running through Sephadex G-25 Fine  keeping the 
same final ratio between iron and any mutant or wild type IPNS proteins.

My additional questions are:
   
   a. Which reason(s) could explain(s) nicely our observation of an 
      'unspecific' iron binding by Isopenicillin N Synthase protein?
                                                                 
   b. Which kind of possible 'preventive' methods could be used to except 
      such 'unspecific' iron binding by Isopenicillin N Synthase protein?

Please, answering me, remember that my speciality is genetics! Please, 
be without very hard comments concerning my 'report'!

Thank anybody in advance for any information.

Ilya Borovok
borovok at ccsg.tau.ac.il
       @post.tau.ac.il