Figure 4.

Covalent labelling of AlbC and variants by [¹⁴C]Phe transferred from [¹⁴C]Phe-tRNA Phe. AlbC was used as positive control for the formation of phenylalanyl-enzyme and S37A was used as a negative control in this experiment (not shown). Enzymes were incubated with labelled aa-tRNA, as described in ‘Materials and Methods’, separated on SDS–PAGE, then transferred onto a PVDF membrane that was analysed with a radioimager. Detection of potential leucyl-enzyme intermediates is shown in Supplementary Figure S5. (A) Variants of the basic patch. (B) Variants of the loops α6–α7 and β6–α8. Proteins were analysed on different gels. AlbC was loaded onto each gel as a standard.