. Author manuscript; available in PMC: 2014 Sep 3.

Published in final edited form as: Biochemistry. 2013 Aug 21;52(35):10.1021/bi400683y. doi: 10.1021/bi400683y

Table 3.

Comparison between α-value and GTFE-based analyses of solute effects on protein processes.

	α-value analysis	GTFE analysis ^22,37
Experimental method for high- solubility model compounds	Vapor Pressure Osmometry	Solubility
Experimental method for low- solubility model compounds	Solubility or micelle formation¹⁷	Solubility
Building blocks of proteins used to quantify solute interactions	Functional groups (aliphatic and aromatic C; carboxylate, amide and hydroxyl O)	Peptide backbone, amino acid side chains
Number of model compounds	Variable (25 for proline, 27 for GB³⁹ 46 for urea¹⁷)	21 (20 amino acids+cGG)
Number of interaction values (α or GTFE/ASA) obtained from analysis	7 (7 functional groups)	20 (19 sidechains+ backbone)
Redundancy of Model Compound Set	Yes	No
Use of Hypothesis of Additivity of contributions	Yes, by unified atom or functional group(Eq. 4)	Yes, by sidechain or backbone
Test of Hypothesis of Additivity	Yes, at solute-functional group level	No
Treatment of counterions of charged amino acids	Separated from sidechain, quantified individually	Treated implicitly with sidechain; not separable
Unfolded state model	All-trans extended (but other models can be used)	Average of extended and structured (but other models can be used)
Uncertainty values	Based on error propagation from α- value uncertainty	Not reported