Table 1. K_m (mM) and V_max (fm product/[μg∙min]) values for methylated product formation: 254C vs 254F hINMT^*.

			Km			Vmax
substrate	allozyme	DTT	ave	SD	-/+DTT: p val†, n	ave	SD	-/+DTT: p value, n
tryptamine	254C	-	1.70	.05		.73	.14
		+	2.91	1.09	0.300, 2	1.74	0.04	0.0114, 2
	254F	-	0.93	0.04		1.02	0.11
		+	1.64	0.13	0.0305, 2	1.09	0.05	0.338, 2
DMS	254C	-	0.81	0.16		5.39	0.43
		+	0.89	0.15	0.133, 2	16.69	1.41	0.0015, 2
	254F	-	0.63	0.20		3.12	2.31
		+	0.62	0.07	0.056, 2	2.21	1.16	0.404, 2
DMSe	254C	-	ND**	ND		ND	ND
		+	0.24	0.13	nd, 3	0.61	0.13	nd, 3
	254F	-	ND	ND		ND	ND
		+	0.26	0.03	nd, 3	0.48	0.15	nd, 3

*, * * values calculated from minimum two assays with duplicate points, ND, not determined

^†Significant difference between (-/+) DTT values for K_m and V_max parameters.

Unpaired t-test comparisons were carried out between the (-/+) DTT values obtained for each substrate/allozyme combination. For example, 254C tryptamine V_max (-) DTT (0.73 ± 0.14) was compared by unpaired t-test to the respective 254C (+) DTT condition (1.74 ± 0.04) resulting in a p value of 0.0114. A significant difference was the result of a P value < 0.05.