Table 2. Estimates of the maximum fraction of the solvent-cavity space occupied by ice in glycerol-free crystals of apoferritin, thaumatin and lysozyme at temperatures between 180 and 220 K, as described in Supplementary Section S8.

	Fraction of internal solvent that forms ice
	Apoferritin	Thaumatin	Lysozyme
Fraction of solvent exiting the unit cell (%)
f exit = 0	59 ± 13	35 ± 6	17 ± 5
f exit, ‘bulk’	45 ± 13	25 ± 6	8 ± 6
f exit, ‘perturbed’	47 ± 13	29 ± 6	12 ± 6
Fraction of solvent >2.8 Å from protein (%)	83	70	29
Fraction of solvent >5.6 Å from protein (%)	55	31	0.5
Estimated thickness of unfreezable layer (Å)	6.6 ± 1.8	6.9 ± 0.9	5.1 ± 1.4