Abstract
The concentrations of oxidized and reduced pyridine nucleotides in tissue extracts can be estimated by an enzyme assay which couples the specific dehydrogenases and a non-specific diaphorase and measures the rate of reduction of 2,6-dichlorphenol-indophenol. The results of these assays agree well with those obtained by a fluorimetric assay and with the assays of Glock and McLean (1955) who used cytochrome c reductases and cytochrome c.