Title: Moog RS, et al. Evidence for methoxatin (pyrroloquinolinequinone) as the cofactor in bovine plasma amine oxidase from resonance Raman spectroscopy. Proc Natl Acad Sci U S A. 1986 Nov;83(22):8435-9.
Title: Bishop A, et al. Methoxatin (PQQ) in guinea-pig neutrophils. Free Radic Biol Med. 1994 Oct;17(4):311-20.