Table 2. Selection of the 35 PDB-derived ligands selected to formulate MORPHEUS II.

Number of structures (i.e. occurrences in the PDB) showing a main chemical as an ordered ligand (as of December 2014). Note that a few reagents that were not found in the PDB were integrated to complete the formulations (the four polyols used as cryoprotectants and five of the six buffers used to formulate the buffer systems).

Chemical name	Type	PDB ID (main)	No. of structures
Lithium sulfate	Common salt	LI	51
Sodium chloride	Common salt	NA	4726
Potassium sulfate	Common salt	K	1638
Manganese chloride tetrahydrate	Divalent cation	MN	1938
Cobalt chloride hexahydrate	Divalent cation	CO	474
Nickel chloride hexahydrate	Divalent cation	NI	699
Zinc acetate dihydrate	Divalent cation	ZN	8413
Barium acetate	Alkali	BA	91
Cesium acetate	Alkali	CS	75
Rubidium chloride	Alkali	RB	34
Strontium acetate	Alkali	SR	101
Sodium chromate tetrahydrate	Oxometalate	CR	7
Sodium molybdate dihydrate	Oxometalate	MOO	20
Sodium orthovanadate	Oxometalate	VO4	73
Sodium tungstate dihydrate	Oxometalate	WO4	47
Erbium(III) chloride hexahydrate	Lanthanide	ER3	2
Terbium(III) chloride hexahydrate	Lanthanide	TB	11
Ytterbium(III) chloride hexahydrate	Lanthanide	YB	57
Yttrium(III) chloride hexahydrate	Lanthanide	YT3	33
Xylitol	Monosaccharide	XYL	25
D-()-Fructose	Monosaccharide	FRU; FUD	36; 4
D-Sorbitol	Monosaccharide	SOR	12
myo-Inositol	Monosaccharide	INS	16
L-Rhamnose monohydrate	Monosaccharide	RAM	43
DL-Threonine	Amino-acid	DTH; THR	23; n/a
DL-HistidineHClH2O	Amino-acid	DHI; HIS	24; n/a
DL-5-HydroxylysineHCl	Amino-acid	n/a; LYZ	0; 7
trans-4-Hydroxy-L-proline	Amino-acid	HYP	149
Spermine4HCl	Polyamine	SPM	105
Spermidine3HCl	Polyamine	SPD	33
1,4-Diaminobutane2HCl	Polyamine	PUT	22
DL-OrnithineHCl	Polyamine	ORD; ORN	3; 56
NDSB 256	Surfactant	DMX	4
NDSB 195	Surfactant	NDS	7
Bis-tris	Buffer	BTB	114