Role of Motif III in Catalysis by Acetyl-CoA Synthetase

Table 2

Kinetic parameters for ACS1_Mt wild-type and variant enzymes.

Enzyme	𝑘cat	𝐾𝑚 acetate	𝐾𝑚 ATP	𝐾𝑚 CoA
	(sec^−1)	(mM)	(mM)	(mM)
Acs1Mt	66.6 ± 0.9	3.5 ± 0.1	3.3 ± 0.2	0.19 ± 0.003
Tyr^498Ala	1.6 ± 0.04	7.5 ± 0.6	1.7 ± 0.3	0.10 ± 0.004
Tyr^498Phe		Inactive^a
Thr^499Ala	0.8 ± 0.01	3.0 ± 0.01	1.7 ± 0.1	0.24 ± 0.01
Ala^500Thr	1.5 ± 0.04	2.1 ± 0.2	3.6 ± 0.1	0.51 ± 0.04
Gly^501Ala	0.3 ± 0.01	1.4 ± 0.1	1.7 ± 0.07	0.08 ± 0.002
Asp^502Ala		Inactive^a
Asp^502Glu		Inactive^a
Asp^502Asn		Inactive^a

^aActivity was tested over a wide range of concentrations for each substrate and at several enzyme concentrations, but no activity was observed.