Thursday, June 18, 2015

053 - Purification to homogeneity of Azotobacter vinelandii hydrogenase: a nickel and iron containing αβ dimer

This study purified and characterized the uptake hydrogenase from Azotobacter vinelandii.

What They Saw
As a single unit, not denatured, the hydrogenase ran as a single band on a gel. On a denaturing gel it was two bands though, 31 and 67 kDa, indicating that it had two subunits, a larger and a smaller (HoxG and HoxK). The whole thing is about 98.6 kDa. This contrasts with previous reports that it was a single subunit of 60 kDa (049), but it's not really clear why there's this discrepancy.

They also measured metal contents, and found 6.6 mol iron and 0.68 mol nickel per mol hydrogenase, so they rounded up to 1 mol Ni and 10 mol Fe, 1:10 ratio.

They also contradicted the previous result that the hydrogenase couldn't donate to acceptors with negative potential. But they confirmed the possibility that hydrogenase produces hydrogen when paired with a very reduced donor, except this peaked at a higher pH (6 to 8.5).


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