TABLE 3.

Riboflavin kinase, FMN hydrolase, and FAD pyrophosphatase activities in pea organelles Enzyme activities were measured in protein extracts of pea chloroplasts and mitochondria at two pH values. Substrate concentrations were 50 μm for riboflavin, FMN, and FAD and 3 mm for ATP. Data are mean ± S.E. of three independent organelle preparations, each assayed in triplicate.

Organelle	Riboflavin kinase	FMN hydrolase	FAD pyrophosphatase
		pmol min–1 mg–1
Chloroplasts
pH 7.5	0.79 ± 0.03	244 ± 35	30.0 ± 2.4
pH 8.5	2.47 ± 0.08	151 ± 4	38.4 ± 4.7
Mitochondria
pH 7.5	7.8 ± 0.8	1393 ± 58	343 ± 44
pH 8.5	15.9 ± 1.7	446 ± 22	482 ± 41