Table 5.

Comparison of the amino acid sequences and specificities of representative mutants from Fab phage-displayed libraries randomized at L chain CDR3 positions 92–94, combined with the insertion of two extra random codons a

Mutants selected from libraries (see Table 3)										Corresponding site-directed mutantsb
	Light-chain CDR3 sequence										Light-chain CDR3 sequence
Fab	91	a	b	92	93	94	95	96	IC50 ratioa digitoxin/ digoxin	Fab	91	a	b	92	93	94	95	96	IC50 ratioc digitoxin/ digoxin
26-10 wt	T			T	H	V	P	P	3	26-10:V94W	T			T	H	W	P	P	0.25
IDGW7	T	N	P	R	L	F	P	P	0.5	IDGW7:F94W	T	N	P	R	L	W	P	P	0.12
IDGW12	T	A	P	V	L	F	P	P	1	IDGW12:P91bA	T	A	A	V	L	F	P	P	1
IDGW14	T	T	P	R	A	W	P	P	0.06	IDGW14:W94F	T	T	P	R	A	F	P	P	2.25
IDGW15	T			L	F	W	P	P	0.18	IDGW15:W94F	T			L	F	F	P	P	1

^a These mutants are among those listed in Table 2, and were obtained following panning on digitoxin–BSA.

^b Mutants are defined using the one-letter code by the residue in the parent, followed by the light-chain position number, followed by the resultant mutant residue. The positions for site-directed mutagenesis are given in bold-face type.

^c Values reported are ratios of molar concentration of inhibitor required to give 50% inhibition of Fab binding to analog–BSA-coated wells, relative to the respective molar concentrations of digoxin.