Table 2. Superposition of the present structures and analysis of common waters.

A C^α superposition was performed between the present structures of thermolysin crystals as shown at the left and top. Amino-acid residues with alternate conformations were excluded from the calculation. The upper value is the r.m.s.d. value of the interatomic distances between corresponding C^α atoms after superposition; 304–309 C^α atoms were used for the calculation. A statistical examination of the positional differences between the distributions of C^α deviations using the Mann–Whitney U-test (Mann & Whitney, 1947 ▸) is available in Supplementary Table S1. After the C^α superposition, the common water molecules with close interatomic distances of less than 1.5 Å were counted. The number of atoms was calculated as the sum of occupancies. The ratio of the number of common waters to the total number of waters in the structure on the left is shown as the lower value.

	Liganded oil–SFX	Liganded water–SFX	Unliganded oil–SFX	Liganded SR1	Liganded SR2
Liganded oil–SFX		0.057 Å	0.106 Å	0.160 Å	0.182 Å
		81.5%	73.9%	73.9%	74.6%
Liganded water–SFX	—		0.112 Å	0.163 Å	0.182 Å
	79.8%		74.1%	70.2%	75.5%
Unliganded oil–SFX	—	—		0.190 Å	0.192 Å
	70.1%	71.8%		67.0%	71.1%
Liganded SR1	—	—	—		0.158 Å
	53.1%	51.5%	50.7%		67.7%
Liganded SR2	—	—	—	—
	43.0%	44.5%	43.2%	54.3%