TABLE 2.

Summary of the biochemical and growth characteristics of clones containing estRB8

Growth temp (°C)	E. coli/pBK1Est				E. coli/pBKCpnEst without esterase inductiona
	Without esterase inductiona		With esterase inductionb
	Expression of EstRB8 (μg/mg)c	Esterase sp actd	Expression of EstRB8 (μg/mg)c	Esterase sp actd	Expression of EstRB8 (μg/mg)c	Esterase sp actd
37	25-50	179	25-50	184	25-50	162
30	25-50	1,894	25-50	1,800	25-50	1,714
20	25-50	7,518	25-50	9,636	25-50	10,362
15	25-50	23,270e	25-50	22,375	25-50	27,523f
10	NDg	ND	12-20	1,188	25-50	31,488h
8	ND	ND	1.2	850	25-50	32,380h
4	ND	ND	<0.1	239	25-50	32,380h

^aAn E. coli strain harboring pBK1Est (without cpn60 and cpn10) or pBKCpnEst (with cpn60 and cpn10) was grown directly at temperatures ranging from 4 to 37°C in the presence of IPTG (1 mM).

^bAn E. coli strain harboring pBK1Est (without cpn60 and cpn10) was grown at 37°C (optical density, 1.0), and esterase activity was induced by addition of IPTG (1 mM) after incubation at suboptimal temperature (37 to 4°C).

^cLevel of expression (in micrograms of EstRB8/per milligram of total protein) in E. coli cell extract (for details see Materials and Methods).

^dSpecific activity (in micromoles per minute per gram of pure protein) in Tris-HCl buffers (pH 9.0) at 20°C when p-NPB was used as the substrate.

^eGrowth rate, 0.15 h⁻¹.

^fGrowth rate, 0.45 h⁻¹.

^gND, no growth or growth rate lower than 0.02 h⁻¹.

^hGrowth rate, 0.28 to 0.36 h⁻¹.