TABLE 1.

Crossover positions for the E. coli/B. subtilis and B. subtilis/L. casei DHFR hybrids and their specific activities (μmol/min/mg)

E. coli/B. subtilis		B. subtilis/L. casei
Crossover position	Specific activity	Crossover position	Specific activity
0	20.22	0	0.197 ± 0.114
32	2.17	32	0.915 ± 0.086
35	0.39	40	0.067 ± 0.008
46	0.17	53	0.001 ± 0.000
49	0.12	62	0.025 ± 0.004
53	0.12	85	0.001 ± 0.000
55	0.12	103	0.003 ± 0.001
62	0.09	114	0.035 ± 0.16
73	0.01	123	0.063 ± 0.005
79	0.15	160	6.622 ± 0.157
81	0.06
96	0.10
100	0.36
108	0.70
122	0.84
159	1.43

The errors in the specific activity for the B. subtilis/L. casei hybrids are given at 95% confidence interval.

The crossover positions for the E. coli/B. subtilis and B. subtilis/L. casei hybrids are defined as the last reside position (in alignment) of the E. coli and B. subtilis DHFR sequences, respectively.