. 2014 Mar 5;53(15):2541–2555. doi: 10.1021/bi401671t

Table 6. Effects of Mutation of Val74, a Residue Situated across the Dimer Interface from the Structured Loop, in WT KSI and in a KSI Mutant with Multiple Residues in the Loop Mutated to Glycine^a.

enzyme	k_cat (s^–1)	K_M (μM)	k_cat/K_M (M^–1 s^–1)	k_cat ratio (WT/mutant)^b	K_M ratio (WT/mutant)^b	k_cat/K_M ratio (WT/mutant)^b
WT	36 ± 2	50 ± 4	(7.2 ± 0.3) × 10⁵	(1)	(1)	(1)
V74G	6.7 ± 2	35 ± 4	(1.9 ± 0.3) × 10⁵	5.4	1.4	3.8
P39G/V40G/S42G	(4.8 ± 0.6) × 10^–2	55 ± 11	(8.7 ± 0.2) × 10²	750	0.9	830
P39G/V40G/S42G/V74G	(7.5 ± 0.2) × 10^–2	35 ± 2	(2.1 ± 0.2) × 10³	480	1.4	340

Kinetics experiments were performed for the 5(10)-EST substrate for which the chemical steps of the KSI reaction are rate-limiting.^4,58

By definition, the ratio for WT KSI is 1, as represented by the values in parentheses.

Table 6. Effects of Mutation of Val74, a Residue Situated across the Dimer Interface from the Structured Loop, in WT KSI and in a KSI Mutant with Multiple Residues in the Loop Mutated to Glycinea.