Table 4.

Kinetic parameters of the selected novel missense mutations in the ELAC2 endonuclease with the pre‐mt‐tRNA^Ile substrate

Mutant	# Trials	Mut. /WT	k cat (min−1)	K M (nM)	k cat /K M (x 108 M−1min−1)	Relative k cat	Relative K M	Relative k cat /K M *
WT	3		0.17 ± 0.05	3.4 ± 1.3	0.57 ± 0.17
Arg564Ser	3	1.1	0.38 ± 0.12	6.5 ± 2.6	0.65 ± 0.10	1.8 ± 0.56	2.8 ± 1.1	0.71 ± 0.11
Arg781His	3	6.7	0.016 ± 0.003	7.1 ± 2.0	0.027 ± 0.01	0.20 ± 0.04	3.8 ± 1.3	0.062 ± 0.01

Column designation, from left: (column 1) Variant: wild‐type (WT) or mutant ELAC2‐; (column 2) number of times variant processing experiments were performed; (column 3) the ratio of mutant to WT concentration depending on the impairment factor. (columns 4–6) k _cat, K _M, k _cat/K _M: values reported are means of replicate experiments. Values following ± are standard errors. (columns 7–9) k _cat, K _M and k _cat/K _M relative to WT (e.g., the quotient [k _cat mutant]/[k _cat WT]). *Reported variant relative to WT values are the means and standard errors for specific experiments performed on the same day, rather than the compiled values at the top of the table, therefore differ from results that would be obtained by comparing values in columns to the left with aggregate means for WT (first row). Regular font: no impairment of enzymatic activity (>0.8 of WT) or not statistically significant. Bold: severe impairment of enzymatic activity (<0.2 of WT).