Table 1.

List of the atoms considered as acceptors and donors. For both classes, the 3-letter codes of the amino acids, the symbol used in the PDB files of the considered atom, and the maximum number of hydrogen bonds of atom are reported.

Acceptors			Donors
all	O	1	all	N	1
ASP	OD1	2	HIS	NE2	1
ASP	OD2	2	HIS	ND1	1
GLU	OE1	2	LYS	NZ	3
GLU	OE2	2	ASN	ND2	2
GLN	OE1	1	GLN	NE2	2
ASN	OD1	1	ARG	NE	1
SER	OG	1	ARG	NH1	2
THR	OG1	1	ARG	NH2	2
			TRP	NE1	1
			SER	OG	1
			THR	OG1	1
			TYR	OH	1