Table 1 Thermodynamic parameters of NADH and NAD+ binding with the αβ, αγ and α2βγ enzymes of human NAD-IDH analyzed by ITC at 20 °C.

From: Insights into the inhibitory mechanisms of NADH on the αγ heterodimer of human NAD-dependent isocitrate dehydrogenase

Protein

K d (μ M) a

ΔH (kcal/mol)

TΔS

n-value

For NADH

αβ (30 μM/0.8 mM)b

4.6 ± 0.7

−16.6 ± 0.7

−9.03

1.26 ± 0.04

αγ (100 μM/4 mM)

109.0 ± 19.5

−8.1 ± 1.3

−2.62

2.19 ± 0.27

α2βγ (30 μM/2 mM)

46.3 ± 6.5

−21.8 ± 2.7

−14.8

2.53 ± 0.25

For NAD+

αβ (200 μM/4 mM)

268.1 ± 28.4

−5.0 ± 0.7

−0.2

1.14 ± 0.11

αγ (100 μM/4 mM)

ND

ND

ND

ND

α2βγ (100 μM/8 mM)

WB

WB

WB

WB

  1. aAbbreviations: K d , dissociation constant; ND, not detectable; WB, weak binding.
  2. bNumbers in parentheses refer to the concentrations of titrand (protein)/titrant (NADH or NAD+) in the measurements.
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