Table 1.

Melting temperatures T_m and transition enthalpies ΔH⁰ of host–guest peptides as determined by CD spectroscopy

Peptide	0 M TMAO		3.7 M TMAO		ΔTm/[TMAO], K/mol/liter
	Tm (°C)*	ΔH0 (kJ/mol)	Tm (°C)	ΔH0 (kJ/mol)
GPO†	44.5	−350	n.d.	n.d.	n.d.
GSO	38.3	−510	47.1‡	−410‡	4.4
GPS	34.8	−440	n.d.	n.d.	n.d.
SPO	8.6	−590	26.5	−350	4.8
APO	9.9	−550	31.9	−380	5.9
CPOred	[−3]	—	18.1	−190	5.6
RPO	[−7]	—	12.2	−320	5.1
VPO	[−10]	—	8.2	−360	n.d.
EPO	[−16]	—	3	−380	n.d.
DPO	[−17]	—	2	−300	n.d.

Data are derived from CD melting curves recorded at 225 nm at peptide concentrations of 1 mg/ml in PBS in the absence and presence of TMAO. Values for the change of T_m with increasing amounts of TMAO are based on measurements performed at varying concentrations by assuming a linear relationship. n.d., not determined. 

*Numbers in brackets are obtained from extrapolation of TMAO data to 0 M TMAO. 

^†Values from ref. 22 are included for comparison. 

^‡Values are for 2 M TMAO, because peptide GSO precipitates at higher osmolyte concentrations.