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. Author manuscript; available in PMC: 2016 Feb 10.
Published in final edited form as: Biochemistry. 2015 Apr 16;54(16):2644–2658. doi: 10.1021/acs.biochem.5b00113

Table 5.

Steady-State Kinetic Constants for the Pro-27 Site-Directed Mutanta

variant varied substrate Km,app (μM) kcat,app (s−1) (kcat/Km)app (M−1 s−1) {[(kcat/Km)app-mutant]/[(kcat/Km)app-wild-type]} × 100 (%)
wild-typeb acetyl-CoA 29 ± 2 32 ± 1   (1.1 ± 0.1) × 106 100         
P27Ab 105 ± 4   0.77 ± 0.02 (7.4 ± 0.3) × 103 0.67
wild-typec histamine 520 ± 54 30 ± 1   (5.8 ± 0.6) × 104 100         
P27Ac 1800 ± 100 0.80 ± 0.02 440 ± 30 0.76
wild-typec agmatine   790 ± 100 0.68 ± 0.03 850 ± 110 100        
P27Ac 1300 ± 100 0.012 ± 0.001 9.7 ± 0.7 1.1
a

Kinetic constants are reported as ± the standard error (n = 3).

b

Reaction conditions: 300 mM Tris-HCl (pH 8.0), 150 μM DTNB, a constant saturating concentration of histamine (>3Km,app), and varying concentrations of acetyl-CoA.

c

Reaction conditions: 300 mM Tris-HCl (pH 8.0), 150 μM DTNB, a constant saturating concentration of acetyl-CoA (>3Km,app), and varying concentrations of amine substrate.