It is pyrroloquinoline quinone, aka PQQ, aka the novel putative vitamin. Historically, many, many compounds have been proposed as vitamins and then withdrawn. This is why the sequence of B vitamins includes B1 thiamin, B2 riboflavin, B3 niacin, B5 pantothenate, B6 pyridoxal, B7 biotin, B9 folate, B12 cobalamin -- B4, B8, B10, and B11 were later withdrawn as were B13, B14, B15, B16 and B17. The jury remains out on PQQ (jury also still out on choline), but let's go to the record.
In 2003, the famous Kasahara and Kato publish a report in
Nature detailing the role of PQQ in lysine metabolism, suggesting it may be a novel vitamin in mammals.
http://www.shanghaimed.cn/bookpic/upFileDown/201051818383010617.pdf (Kasahara and Kato, 2003)
Two years later, two papers in
Nature, one by Rucker et al, one by Felton and Anthony, attack this hypothesis. Rucker states that PQQ status does not affect the presence or absence of lysine-metabolizing enzymes, a biomarker for lysine metabolism. Fenton and Anthony state that the proposed PQQ-dependent enzyme was misidentified, and has a novel structure but does not use PQQ.
Nature was furious, and published both.
http://www.nature.com/nature/journal/v433/n7025/abs/nature03323.html (Rucker et al 2005)
http://www.nature.com/nature/journal/v433/n7025/abs/nature03322.html (Fenton and Anthony 2005)
The next year, Bauerly et al publish a report in
Biophysica Acta confirming K&K and stating that PQQ status does indeed affect lysine metabolism, regardless of alpha-aminoadipate semialdehyde dehydrogenase! The authors go on to state that PQQ's known, novel and poorly understood role in mitochondriogenesis -- the generation of new mitochondria -- may explain its role in lysine metabolism.
Nature has had more than enough of this bullshit.
http://cat.inist.fr/?aModele=afficheN&cpsidt=18265312 (Bauerly et al 2006)
In 2009, Rucker, Chowanadisai and Nakano -- the same Rucker as before -- publish an article in
Alternative Medicine stating "PQQ is a novel biofactor for which a proposition can be made for physiological importance." Again he cites the role of PQQ in mitochondriogenesis. This represents a partial -- mind you I said
partial -- reversal of Rucker's initial position, but
not a suggestion that PQQ is a mammalian enzyme cofactor:
http://www.researchgate.net/publica...quinoline_quinone/file/d912f50609e366fa89.pdf (Rucker et al 2009)
Anthony, by contrast, remains firmly in the "not a cofactor, not a vitamin" camp, with a well-cited presentation on his website of why he thinks so.
http://www.chris-anthony.co.uk/myresearch.html#pqqvit
So, is PQQ vital to life?
http://www.youtube.com/watch?v=fpaQpyU_QiM
This was originally posted as a response to a thread in Basic Drug Discussion
i've just bought my child some clothes for her weekend away with some family members (first time she's been away since she was born 5 years ago. 
"More more more" said the old wise man.
