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. 2001 May 1;98(10):5578–5583. doi: 10.1073/pnas.091100898

Table 2.

Thermal unfolding and sedimentation analysis of trpzip peptides

Parameter trpzip1 trpzip2 trpzip3 trpzip4 trpzip5 trpzip6
Tm, K 323.0  ± 0.3 345.0  ± 0.1 351.8  ± 0.2 343.1  ± 0.1 315.8  ± 0.2 317.7  ± 0.5
ΔHm, cal⋅mol−1 10,790  ± 120 16,770  ± 60 13,020  ± 70 21,860  ± 60 13,320  ± 140 10,290  ± 300
ΔSm, cal⋅mol−1⋅K−1 33.4 48.6 37.0 63.7 42.2 32.4
ΔCp, cal⋅mol−1⋅K−1 231  ± 4 281  ± 2 195  ± 2 380  ± 4 325  ± 10 236  ± 17
σobscalc 1.02  ± 0.04 1.01  ± 0.04 1.00  ± 0.04 n. d. n. d. n. d.

Thermal melts were acquired with 20 μM peptide samples in 20 mM potassium phosphate, pH 7.0. σ ≡ reduced apparent molecular weight, as determined from sedimentation data fit to a nonideal single-species model (see Materials and Methods). n.d. ≡ not determined; the thermal denaturation curve of trpzip4 was identical at 5-fold higher peptide concentration (100 μM vs. 20 μM). Thermal unfolding parameters of ΔH = 11,600 cal⋅mol−1 and ΔS = 39 cal⋅mol−1⋅K−1 have been reported for the gb1 peptide, assuming ΔCp = 0 (7; see also Materials and Methods). 

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