Table 1.

Substrate specificity of apoplastic CKX enzymes of Arabidopsis in dehydrogenase (ferricyanide, FC) and oxygen (O₂) mode at pH 6.0 given as relative activities

Substrate	CKX2		CKX4		CKX6
	FC	O2	FC	O2	FC	O2
iP	100	100	100	100	100	100
2MeSiP	29	19	48	52	54	21
cZ	9	—	24	—	35	—
2MeScZ	2	—	9	—	17	—
tZ	30	111	83	97	30	56
2MeStZ	52	15	17	38	42	69

All data represent mean values of at least 2 biological replicates. Deviations between replicates did not exceed 10%; dashes, oxidative degradation of cis-derivatives could not be determined (see Materials and Methods).