TABLE 2.

Conserved residues in class A β-lactamases

Location of residueg	% conserved residues
	Reported by:			Totald	Subclass A1e	Subclass A2f
	Ambler et al.a	Matagne et al.b	Risso et al.c
37E	100	89	88	77	97	28
45G	100	100	97	97	99	96 G/A
66F	100	96	91	88	99	80 Y/F
70S	100	100	100	100	100	100
73K	100	100	100	100	100	100
81L	100	96	90	95	99	80 L
107P	100	100	93	97	97	94
130S	100	100	100	99	99	100
131D	100	100	100	100	100	100
132N	95	96	97	95	96	90
134A	100	100	96	90	98	91 A/G
136N	100	93	91	79	99	94 D
144G	100	96	96	95	97	90
156G	100	93	97	93	95	85
157D	100	91	83	78	99	58I
164R	100	89	79	73	92	34 A
166E	100	100	93	100	100	100
169L	100	91	77	76	93	81 M
179D	100	91	78	77	97	99 N
180T	100	91	79	76	95	80 W/Y
199L	100	93	92	90	98	80
207L	100	93	82	86	88	100 L/I
233D	100	91	85	75	93	99 H/R
234K/R	100	100	100	100	100	100
235T/S	100	100	97	99	100	99 T
236G	100	100	100	100	100	100

^aTwenty representative enzymes were examined (96).

^bForty-six representative enzymes were examined (12).

^cSeventy-five putative enzymes were examined (97).

^dThere were a total of 268 representative and putative enzymes.

^eThere were a total of 213 representative and putative enzymes for subclass A1.

^fThere were a total of 55 representative and putative enzymes for subclass A2.

^gMajor residues involved in the catalytic mechanism and/or in substrate binding are shown in boldface type (12).