Structure-Based Mechanism for Early PLP-Mediated Steps of Rabbit Cytosolic Serine Hydroxymethyltransferase Reaction

Table 2

Kinetic constants for the rate of formation and breakdown of the gem-diamine complex for mutant rcSHMT forms with glycine and L-serine substrates.

Substrate	pH	T253A			T253C
		𝑘on (s^−1 M^−1 · 10^4)	𝑘^′on  (s^−1 M^−1 · 10^6)	𝑘off  (s^−1)	𝑘on  (s^−1 M^−1 · 10^4)	𝑘^′on; (s^−1 M^−1 · 10^6)	𝑘off; (s^−1)
L-Serine	6.4	3.3	20	10.3	2.9	18	39
	6.8	5.8	14	8.3	4.0	10	36
	7.2	8.7	8.6	5.8	6.8	6.7	32
	7.6	9.5	3.7	5.3	8.7	3.4	27
	8.0	10.7	1.8	3.1	9.4	1.5	23
Glycine	6.4	0.8	13	1.0	0.5	8.5	5.1
	6.8	1.3	8.0	1.3	0.7	4.5	6.7
	7.2	2.1	5.0	1.9	1.5	3.8	6.9
	7.6	3.0	2.9	2.4	2.1	2.2	7.0
	8.0	4.4	1.8	2.9	3.7	1.6	6.8