Table 3 Steady-state Kinetic Constants for Amine Substrates at a Fixed Initial Concentration of Acetyl-CoAa ,b.

From: Structural and Mechanistic Analysis of Drosophila melanogaster Agmatine N-Acetyltransferase, an Enzyme that Catalyzes the Formation of N-Acetylagmatine

Substrate

Km, app (mM)

kcat, app (s−1)

(kcat/Km)app (M−1s−1)

Agmatine (0.1–5.0 mM)

0.30 ± 0.02

18 ± 1

(6.0 ± 0.5) × 104

Spermine (2.5–500 mM)

18 ± 3

77 ± 7

(4.0 ± 1) × 103

N 8-acetylspermidine (0.5–50 mM)

9.1 ± 1

32 ± 2

(4.0 ± 1) × 103

Putrescine (1.0–500 mM)

51 ± 3

7.7 ± 0.3

150 ± 9

Spermidine (5.0–500 mM)

17 ± 0.5

1.3 ± 0.009

76 ± 0.5

Cadaverine (2.5–1000 mM)

32 ± 6

1.0 ± 0.1

32 ± 6

  1. aKinetic constants are reported as ± standard error (n = 3). bReaction conditions −300 mM Tris-HCl pH 8.5, 150 µM DTNB, 500 μM acetyl-CoA, and varying concentration of amine substrate. che range of amine concentrations used in determining the Km,app values at the constant, fixed initial concentration of acetyl-CoA (500 μM).
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