Enhancement of thermostability of firefly luciferase from Luciola lateralis by a single amino acid substitution.

We constructed firefly luciferase mutants from Luciola lateralis in which Ala at position 217 was replaced by each of three hydrophobic amino acid residues (Ile, Leu, and Val). These mutants were superior to the wild-type in thermostability. Especially, the purified Ala217Leu mutant still maintained over 70% of the initial activity after 60 min at 50 degrees C. This mutant is the most thermostable firefly luciferase obtained.