Pyrroloquinoline Quinone (PQQ)

Pyrroloquinoline quinone (PQQ) was discovered by J.G. Hauge as the third redox cofactor after nicotinamide and flavin in bacteria. Anthony and Zatman also found the unknown redox cofactor in alcohol dehydrogenase and named Methoxatin. In 1979, Salisbury and colleagues as well as Duine and colleagues extracted this prosthetic group from Methanol dehydrogenase of methylotrophs and identified its molecular structure. Adachi and colleagues identified that PQQ was also found in Acetobacter.

These enzymes containing PQQ are called quinoproteins. Glucose dehydrogenase, one of the quinoproteins, is used as a glucose sensor. Subsequently, PQQ was found to stimulate growth in bacteria. In addition, antioxidant and neuro-protective effects were also found.PQQ may stimulate growth of plants in hydroponic culture and may be the causative factor in plant growth stimulation by a strain of Pseudomonas fluorescens bacterium.