We found a recent paper (
1
) that would be valuable in the field of protein thermodynamics. However, the paper contains some calculation errors. Here, we discuss the errors. Following the notations in Table 2 of the paper, the ensuing relationship of entropy can be established.TΔS0Maltose: MBP + TΔS0MBP: sAB-11M in 1 mm maltose = TΔS0MBP: sAB-11M + TΔS0Maltose: MBP in 5-fold molar excess sAB-11M. Plugging the corresponding values reported in Table 2 of the paper to the equation does not satisfy the equality: 10.4 + (−2.0) ≠ 5.6 + 2.0 (in kcal/mol).
Secondly, there are errors made in the calculation of ΔG0 in Table 2. Based on the equation, ΔG0 = ΔH0 − TΔS0 (
2
), we found that ΔG0MBP: sAB-11M in 1 mm maltose = −14 − (−2) = −12 kcal/mol, not −11.4 kcal/mol as stated in the paper.ΔG0Maltose: MBP in 5-molar excess of sAB-11M = −8.9 − 2 = −10.9 kcal/mol, not −11.1 kcal/mol. ΔG0Maltose: MBP in 5-molar excess of sAB-P1 = −14 − (−1.0) = −13 kcal/mol, not −12.6 kcal/mol.The third error we found is with KD for the binding of MBP to sAB-P1 in 1 mm maltose in Table 2: KD = exp (ΔG0/RT) = exp(−11,000 cal/mol × 4.184J/cal/(8.314 J/mol K × 298.15 K)) = 8.6 nm, not 0.9 nm as in the paper. Lastly, Kmal and KsAB in Fig. 5 are 0.83 × 10−6 m and 0.47 × 10−6 m, not 0.83 × 10−3 m and 0.47 × 10−3 m, respectively.
References
- Engineered synthetic antibodies as probes to quantify the energetic contributions of ligand binding to conformational changes in proteins.J. Biol. Chem. 2018; 293 (29321208): 2815-2828
- Physical Chemistry for the Chemical and Biological Sciences.University Science Books, Sausalito, CA2000
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Published online: April 06, 2018
Edited by Luke O'NeillFootnotes
The authors declare that they have no conflicts of interest with the contents of this article.
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