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. Author manuscript; available in PMC: 2012 Mar 15.
Published in final edited form as: Biochemistry. 2011 Feb 9;50(10):1582–1589. doi: 10.1021/bi1018545

Table 3.

The active site loop closing and opening barrier heights and enthalpy difference, ΔH = Hclosed – Hopen, with bound pyruvate•NADH.

ΔH‡C, kcal/mole ΔH‡O, kcal/mole ΔH, kcal/mole
No osmolyte 9.7±1.0 2.2±1.0 7.8±0.4
TMAO, 1 M 5.3±1.1 −6.2±1.1 11.3±0.5
Urea, 1 M 14.0±2.0 6.2±2.1 8.0±0.8

ΔH‡C is the loop-closing enthalpy barrier derived from k−5 Eyring plot. ΔH‡O is the loop-opening enthalpy barrier derived from k5 Eyring plot. ΔH is the enthalpy difference derived from the Arrhenius behavior of K5 = k5 / k−5.