Measuring the Cytochrome 𝑐 Nitrite Reductase Activity—Practical Considerations on the Enzyme Assays

Table 1

Kinetic parameters for nitrite reduction catalysed by D. desulfuricans ccNiR obtained by the continuous spectrophotometric and the amperometric assays.

	Homogeneous			Electrochemical
Mediator/ Potential (vs NHE)	KM^app (𝜇M)	kcat^app (s^−1)	kcat/KM (s^−1⋅𝜇M^−1)	KM (𝜇M)	kcat (s^−1)^∗	kcat/KM (s^−1⋅𝜇M^−1)
Phenosafranine/−255 mV	2.7±0.4	79±3	29	9.2±0.1	120±1	13
Diquat/−350 mV	6.4±0.6	1064±23	166	28.1±0.4	382±2	14
Methyl viologen/−440 mV	15.0±3.6	738±45	49	33.3±0.7	762±4	23

^∗Turnover number was determined according to [30].