Amperometric detection of histamine at a quinoprotein dehydrogenase enzyme electrode

Methylamine dehydrogenase, a tryptophan tryptophyl quinone (TTQ) containing quinoprotein, catalyzes the oxidation of a variety of primary aliphatic monomaines and diamines to their respective aldehydes and ammonia. This paper reports the construction and characterization of an enzyme electrode capable of detecting histamine and methylamine at +200 mV versus a saturated calomel reference electrode. The methylamine dehydrogenase isolated from Paracoccus denitrificans was used in conjunction with the insoluble mediator tetracyanoquinodimethane (TCNQ) to construct enzyme electrodes which will potentially provide simple rapid analysis of histamine without the need for the extensive sample pretreatments currently required in HPLC and GLC analysis. The linear response of this amperometric sensor, between 0 and 200 microM, correlates well with elevated histamine levels predominant in patients with chronic myelogenous leukaemia, whilst the observed limit of detection, 4.8 microM, compares favourably with the lower limits of detection reported for a potentiometric histamine sensitive enzyme electrode.