Catalase

[Marc Brutschy]

Please forgive a chemist for perhaps picking the wrong newsgroup for 
this question.  I've tried sci.chem and no one has responded.  :-(

Can anyone tell me if the enzyme catalase is metal-based?  I am trying 
to track down the source of contamination in an ultra-trace metals 
analysis (part per billion level).  Someone I work with said she thought 
catalase, which I use to eliminate excess hydrogen peroxide, is based on 
heme (containing Fe).

The catalase I use (from SIGMA) is dark green, suggesting possibly Cu or 
Fe.  I have to acidify my samples with nitric acid to pH2 after I add 
catalase, and I'm worried that when I denature the protein I release 
the metal into my samples.  My reagent blanks are surprisingly high in 
Cu.  This could be from many sources, but I'm specifically worried about 
catalase.

Any help would be *greatly* appreciated.  Please respond by e-mail, if 
possible.  I would read these news groups more often, but I have no idea 
what any of you are talking about!   :-P

Thanks!

Marc Brutschy
brutschy at ix.netcom.com