Table III. Key characteristics of residues of human p53 protein used in the study.

p53 core domain residues and mutationsa	Location in the structure	Solvent accessibility of side chain in wild type (%)b	Cancer occurrence of mutant p53 (%)c	Occurrence of wt residue in the p53 family (%)d
T123A	End of L1 loop, adjacent to S2–S2′ hairpin	46.0	0	92
V143A	S3 strand, hydrophobic core of the β-sandwich, closest to the DNA-binding interface and near the loop–sheet–helix motif	0.2	0.5	69
H168R	L2 loop between β-strands S4 and S5, near the zinc binding site and α-helix	34.2	0.4	77
G245S	L3 loop, between β-strands S8 and S9, critical for backbone conformation (allowing formation of 2 H-bonds with C247, a zinc ligand and R249)	34.5	3.4	100
R249S	L3 loop, adjacent to the minor groove contact residue Arg248, between β-strands S8 and S9 in the sandwich	13.4	3.8	96
N239Y	L3 loop between β-strands S8 and S9, adjacent to the zinc co-ordinating Cys238 and Cys 242 in the same loop	17.7	0.6	93
N268D	S10 strand, which participates in the small three-stranded sheet and in the β-sandwich	13.8	0.07	61

^aThe position according to the sequence of the human 53 protein and the PDB (1tsr).

^bSolvent accessibility (%), defined as solvent-accessible surface area of the amino acid residue in its parent protein calculated by WHATIF, divided by the solvent accessibility of that residue in an extended Ala-X-Ala peptide.

^cThe relative frequency of occurrence of the mutant residue found in cancer was calculated from the p53 database.

^dThe frequency of occurrence of wt residue (%) in other p53 family proteins was calculated based on the sequence alignment of 28 different species using human p53 residue as a reference (Soussi and May, 1996). We also used the sequences of human p40, human p51, human p73, human p63 and rat Ket proteins.