Phenazine methosulfate (PMS) serves as an electron carrier in enzymatic assays (1). Its application has to be carefully checked, because it may negatively influence the assay system. PMS may promote the non-enzymatical conversion of NADPH to NADP+ (5). NAD- and NADP-dependent dehydrogenases will be inhibited in most tissues by PMS. This might be helpful for the examination of NAD- and NADP-independent dehydrogenases and NADH- and NADPH-dependent dehydrogenases, respectively (1, 4).
Stability: PMS solution detoriates in light. The incubation, therefore, should be carried out in the dark (2). Solutions in PBS (e. g. 5 mM corresponding to 1.53 mg/ml) are stable at +4°C for approximately 3 months (3) or in 0.1 mM HCl (14 mg/ml PMS) for approximately 4 weeks (4) if they are protected from light.