Table 2.

The steady-state and single turnover kinetic parameters for BirA-catalyzed biotin transfer to BCCP87

BirA variant	KM(BCCP) (µM)a	kcat (s−1)a	kcat/KM(M−1s−1)b	k1 (M−1s−1)c
Wild Type	9 ± 1	0.060 ± 0.003	6700± 800	12,800 ± 800
E140A	8 ± 3	0.07 ± 0.01	8800± 3500	13,900 ± 800
Q141A	9 ± 1	0.07 ± 0.02	7800 ± 2400	16,000 ± 1000
G142A	214 ± 9	0.05 ± 0.02	230 ± 90	440 ± 10
P143A	13 ± 1	0.070 ± 0.005	5400 ± 600	14,500 ± 1200
R170A	16 ± 2	0.080 ± 0.002	5000± 600	13,700 ± 800
V171A	23 ± 6	0.050 ± 0.003	2200 ± 600	1100 ± 100
K172A	N.D.d	N.D.	N.D.	320 ± 50
N175A	N.D.	N.D.	N.D.	4100 ± 100
D176A	N.D.	N.D.	N.D.	20 ± 2
G193A	11 ± 3	0.070 ± 0.005	6400 ± 1800	12,000 ± 1000
K194A	64 ± 9	0.090 ± 0.005	1400 ± 200	700 ± 100
T195A	19 ± 3	0.07 ± 0.01	3700 ± 800	10,400 ± 800
G196A	8 ± 1	0.070 ± 0.005	8700 ± 1300	5000 ± 100
D197A	12 ± 2	0.08 ± 0.01	6700 ± 1400	17,000 ± 1000
I280A	12 ± 1	0.0600 ± 0.0003	5000± 400	12,500 ± 600
G281A	20 ± 2	0.09000 ± 0.00005	4500± 500	14,000 ± 1000
D282A	9 ± 2	0.060 ± 0.003	6700 ± 1500	14,400 ± 800
K283A	17 ± 1	0.050 ± 0.001	2900 ± 200	10,100 ± 500

The k_cat, K_M and k₁ values were measured as described in Materials and Methods in Standard Buffer (10 mM Tris HCl, pH 7.50±0.02 at 20°C, 200 mM KCl, 2.5 mM MgCl₂)

^aThe errors represent the standard error of two independent experiments

^bThe reported uncertainties were calculated using standard error propagation

^cThe errors represent the uncertainties in the linear regression of the k_obs versus [apoBCC87] profiles.

^dN.D.-Not Determined because these variants were incapable of catalyzing bio-5’-AMP synthesis.