Subject: Structure of Catalase and where active site found

I've just finished an experiment involving the enzyme catalase 
and H2O2.  I was wondering if anyone could provide me with a 
picture of catalase and maybe show where the active site is 
found.  I'm also curious as to the signifigance of the heme on  
catalase and the purpose of the Fe in the middle.  Where 
does the heme bond to catalase?  Also, what cellular processes 
produce H202.  My experiment involved the rate of reaction of 
catalase, any other relevent information would be greatly 
appreciated.  Thank you for your time.

Re: Structure of Catalase and where active site found