Ubiquinone for Mitochondrial Complex I Assays?

[Paul S. Brookes.]

We're troubleshootiing a spectrophotometric mitochondrial complex I (NADH 
ubiquinone oxidoreductase) assay, and suspect that one problem may be the 
ubiquinone we're using.  It's Sigma Decylubiquinone (cat# D7911) which is 
listed as 2,3-dimethoxy-5-methyl-6-decyl-1-4-benzoquinone).   I got this a 
few months back because they didn't have any Co-enzyme Q2 (cat# 
C8081).  The two compounds are essentially the same, except the Q2 has 
geranyl instead of decyl units.  I cannot see how this would affect the 
performance of the "business" end of the Q molecule.

So, has anyone squared these two compunds off in a complex I assay?  Which 
one works best?  Is it remotely feasible that our use of the decyl compound 
is responsible for the assay not working?  We've tried just about 
everyhting else.  Even the positive control (isolated heart mito's at 
1mg/ml in the assay cuvet) will not work.

_________________________________________
Dr. Paul S. Brookes.            (brookes at uab.edu)
UAB Department of Pathology,   G004 Volker Hall
1670 University Blvd., Birmingham AL 35294 USA
Tel (001) 205 934 1915     Fax (001) 205 934 1775
http://peir.path.uab.edu/brookes

Freudian slip - when you say one thing but mean a mother
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