Table 2.

pMMO Activity Data

Sample	Methanotroph	Substrate	Reductant	Turnover number per protomer (s−1)	Specific activity (nmol mg total protein−1 min−1)	Refs
Cells producing pMMO	M. capsulatus (Bath)	propylene	formate	1.4−2.5a	167–300	136,162
	M. trichosporium OB3b	methane	NA	0.68–2.5b	82–300	28,357
Membrane-bound pMMO	M. capsulatus (Bath)	methane	NADH	0.083–0.146c	40–70	59,154
			duroquinol	0.025–0.042d	12−20	59,154
		propylene	NADH	0.044–0.246e	21–118	136,173
			duroquinol	0.033−0.179e	16−86	136,173
	M. sp. Rockwell	methane	NADH	0.017–0.024d,f	8–11.5	59,179
			duroquinol	0.004–0.006d,f	1.8–3	59,179
	M. alcaliphilum 20Z	methane	NADH	0.006c,f	3	154
			duroquinol	0	0	154
Purified pMMO in DDMg	M. capsulatus (Bath)	methane	NADH	0	0	154
			duroquinol	0.002h,i	1	60,154
	M. capsulatus (Bath)	propylene	NADH	0	0	136,173
			duroquinol	0.032–0.21i,j	18–126	136,173
	M. sp. Rockwell	methane	NADH	0	0	59
			duroquinol	0	0	59
	M. alcaliphilum 20Z	methane	NADH	0	0	154
			duroquinol	0	0	154
Purified pMMO in bicelles	M. capsulatus (Bath)	methane	NADH	0.009f,g	5.2	154
			duroquinol	0.006f,h	3.5	154
	M. alcaliphilum 20Z	methane	NADH	0	0	154
			duroquinol	0.007f,h	4.4	154
Purified pMMO in nanodiscsi
DMPCg	M. capsulatus (Bath)	methane	duroquinol	0.005h	3	60
POPCg	M. capsulatus (Bath)			0.009h	5.4	60
native lipids	M. capsulatus (Bath)			0.012h	7.2	60
POPCg	M. sp. Rockwell	methane	duroquinol	0.011g	6.6	179
POPCe	M. alcaliphilum 20Z	methane	duroquinol	0	0	60

^aCalculated from rate of propylene epoxidation monitored by gas chromatography (GC) and assuming pMMO is 20% of the total protein.

^bCalculated from rate of methane uptake and assuming that pMMO is 20% of the total protein.

^cCalculated from rate of conversion of 13CH4 to ¹³CH₃OH monitored by GC/mass spectrometry (GC/MS) and assuming that membrane-bound protein is 80% pMMO.

^dCalculated from rate of conversion of CH₄ to CH₃OH monitored by GC and assuming that membrane-bound protein is 80% pMMO. Values from ref 59 were converted to ¹³C values by applying a correction factor of 0.5.¹⁵⁴

^eCalculated from rate of propylene epoxidation monitored by GC and assuming that membrane-bound protein is 80% pMMO.

^fActivity assay was performed at 30 °C. All other activity assays were performed at 45 °C.

^gAbbreviations used: DDM, n-dodecyl-β-D-maltoside; DMPC, 1,2-dimyristoyl-sn-glycero-3-phosphocholine; POPC, 1-palmitoyl-2-oleoylphosphatidylcholine.

^hCalculated from rate of conversion of ¹³CH₄ to ¹³CH₃OH monitored by GC/MS.

ⁱThe samples used for the M. capsulatus (Bath) pMMO crystal structure determination were not assessed for methane oxidation activity and did not exhibit propylene epoxidation activity.¹⁵¹

^jCalculated from rate of propylene epoxidation monitored by GC.