FAILURE TO VERIFY THE PRESENCE OF PYRROLOQUINOLINE QUINONE (PQQ) IN BOVINE PLASMA AMINE OXIDASE BY GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

The presence of covalently bound pyrroloquinoline quinone (PQQ) in bovine plasma amine oxidase (BPAO) was examined by the use of gas chromatography/mass spectrometry. The enzyme was subjected to proteolysis with proteinase in the presence of [U-13C]PQQ as an internal standard. After isolation and derivatization of PQQ with phenyltrimethylammonium hydroxide, molecular peaks at m z 448 and 462 were used for detection of PQQ and [U-13C]PQQ, respectively, by selected ion monitoring (SIM). In the SIM profile, although the sample extract obtained from BPAO treated with proteinase clearly showed the peak at m z 462 for the internal standard, there were no peaks detectable at m z 448, showing the absence of PQQ in the proteolysis digest of BPAO. Thus, our results do not support the claim that BPAO contains covalently bound PQQ in its structure. © 1990.