MUTAGENESIS OF FIREFLY LUCIFERASE SHOWS THAT CYSTEINE RESIDUES ARE NOT REQUIRED FOR BIOLUMINESCENCE ACTIVITY

Conflicting reports exist in the literature as to whether sulfhydryl g roups are essential for firefly luciferase activity. Inactivation of P hotinus pyralis luciferase with N-tosyl-L-phenylalanine chloromethyl k etone (TPCK) and site-directed mutagenesis demonstrate that the cystei ne residues are not absolutely required for activity. However, loss of P. pyralis luciferase activity is observed when any of the 4 cysteine residues is replaced with serine. (C) 1997 Federation of European Bio chemical Societies.