Table 1.

Kinetic constants for the hydroxymethyltransferase and retro-aldol cleavage reactions catalyzed by wild type and T254 mutant rcSHMT forms.

Substrate	Kinetic constant	Form of rabbit cytosolic SHMT
		Wild type	T253A	T253C
L-Serine	K m (mM)	0.3	0.6	0.5
	k cat (min−1)	850	18.5	1.6
L-allo-Threonine	K m (mM)	1.5	2.5	2.6
	k cat (min−1)	130	14.3	4.5