Table 4.

PMT activities of DsSPDS1 and DsPMT mutants; DsSPDS1 wild type and DsPMT wild-type activities for comparison.

Enzyme	Exchanges	vmax[pkat mg−1]	Km putrescine [μM] Km SAM [μM]	kcat [1 s−1]
DsSPDS1 mutant	D103I	24 ± 6.12	n.d.	0.84 x 10−3
	D103I,	242 ± 6.32	48 ± 6.68	8.48 x 10−3
	Q79T		31 ± 3.42
	D103I,	4338 ± 170.50	159 ± 27.29	0.15
	Q79T,		27 ± 2.99
	V106T
	D103I,	146 ± 17.40	n.d.	5.12 × 10−3
	Q79T,
	V106T,
	L70H
DsSPDS1 wild type (Biastoff et al., 2009b)		12,500	33	0.44
			64 (dcSAM)
DsPMT wild type		51,238 ± 1420	190 ± 27.67	1.98
			13 ± 1.97
DsPMT mutant	H108L	20,035 ± 661	3130 ± 732.59	0.78
			99 ± 11.68

None of the mutants showed SPDS activity. n.d., not determined; n = 3–4 ± standard error.