http://forums.phoenixrising.me/index.php?threads/b2-i-love-you.15209/page-42#post-532708 B2I love you
aaron_c:I feel like I have not been thinking about b2 use as a cofactor in the right sense, so I wanted to share what I found.
The question I had recently is what Christine/DogPerson meant by B2 being “used up” by various other vitamins. Is it used up like ATP gets used up and becomes ADP? Or is it used up because there are more enzymes that require FMN (flavin mononucleotide, aka riboflavin-5-phosphate) as a prosthetic group--meaning it is more like a wrench that all flavoproteins (proteins using FMN or FAD) have to share.
At least in the case of recycling vitamin k via
http://en.wikipedia.org/wiki/NADPH:quinone_reductase, and B6 by
http://en.wikipedia.org/wiki/Pyridoxine_5'-phosphate_oxidase, the FMN is not “used up,” but is simply necessary for the enzyme to function. I also found an entry for a quinone oxidoreductase that did not mention NAD(P)H as a reactant...but looking around on biogps.org, all I could find was something that probably used NADPH...
What I take from all this is that the reason why B2 can take time to go from depleted to replete is that it is “stored” in the enzymes that use it. Obviously the picture is somewhat more complicated. It seems to me like b2 acts a little like something that is stored and a little like something that gets excreted fairly quickly.
Nonetheless, for me seeing this calls into question Christine/DogPerson’s assertion that taking B6 or vitamin K “uses up” B2. In the short term, as an increase in vitamin K might necessitate an increase in vitamin k-dependent proteins, I can see this happening. But once the necessary tools have been made, I am not sure how much more than normal one would need B2.
Of course, those of us with ME have some weird biochemistry, so I do not mean to say that we do not need B2 at all...and this does not necessarily contradict the idea that we would want a fairly high amount. But I am saying that sober husbandry of B2 might not be a reason to avoid increasing B6 and vitamin k.
My understanding of chemistry is not fantastic, so I welcome any corrections!