TABLE 2.

Production level and specific activity of cysteineless AspT variant relative to those of the AspT-His₆ variant

Variant	Production (%)a	Sp act (%)b
AspT-His6	100.0	100.0
Cysteineless AspT	55.7 ± 0.8	74.9 ± 6.7

^aProduction is expressed relative to that of the AspT-His₆ parent as the mean ± standard deviation.

^bThe initial rate of l-[2,3-³H]aspartate transport, normalized for the level of AspT production, is expressed relative to the rate for the AspT-His₆ parent, whose activity was 8.37 nmol min⁻¹ mg of protein⁻¹. The data are the mean ± standard deviation for three independent trials. For each variant, the same amount of protein was used for reconstitution in l-aspartate-loaded proteoliposomes.