1-Methoxy-5-methylphenazinium methyl sulfate. A photochemically stable electron mediator between NADH and various electron acceptors.

This paper describes the properties and application of 1-methoxy-5-methylphenazinium methyl sulfate (1-methoxyPMS), which is a photochemically stable, versatile electron carrier. Like 5-methylphenazinium methyl sulfate (PMS), it mediates electron transfer between NADH and various electron acceptors such as tetrazolium dyes or the electrode of an enzymic electric cell, and yet it does not deteriorate upon storage under scattered light in normal laboratories. The rate of reduction of 1-methoxyPMS coupled to the reoxidation of NADH produced by the lactate dehydrogenase reaction, was even faster than that of PMS. It was also successfully employed as an electron mediator in the enzymic electric cell method for the assay of NAD-linked dehydrogenases. 1-MethoxyPMS solution is rosy pink, and its standard redox potential (E0') is approximately +0.063 V. The use of 1-methoxyPMS will be beneficial in biochemistry as well as medical technology, where PMS has been used as an electron mediator in various electron transfer systems.