Scientists first isolated PQQ from bacteria in 1979. The compound was also thought to be important to mammals, but its precise biochemical pathways remained unclear. In the new work, Takaoki Kasahara and Tadafumi Kato of the Institute of Physical and Chemical Research in Japan elucidate PQQ's role in degrading the amino acid lysine in mice. They found that PQQ generates an enzyme that is required for the reaction to occur. Animals that were deprived of PQQ grew more slowly than their well-fed counterparts did and had fragile skin and compromised immune systems, the researchers found. In addition, the PQQ-lacking mice did not reproduce as well as normal mice did. The authors conclude that PQQ "therefore qualifies as a newcomer to the B group of vitamins." The human body cannot produce most vitamins, but plenty of PQQ can be found in a balanced diet that includes vegetables or meat.