A sensitive and reliable high-throughput approach to screen lipoxygenase (LOX) mutants was developed
to permit a directed evolution study in an attempt to increase the activity and thermostability of LOX
from Anabaena sp. PCC 7120 using error-prone polymerase chain reaction (PCR) and DNA shuffling. The
best mutant, named D22, contained one key amino acid change (N305D) and its half-life of inactivation
at 50 ◦C was increased by approximately twofold in comparison to the wild-type enzyme, while specific
activity 1.87-fold higher than the wild-type enzyme. The N305D substitution was confirmed to be critical
for the thermostability and catalytic activity of LOX by site-saturation mutagenesis. Indeed, the reaction
temperature for maximum activity increased from 45 ◦C to 50 ◦C, while catalytic efficiency (kcat/Km) was
increased by 83%. This study reports for the first timeThe activity and thermostability of the LOX from Anabaena sp.
PCC 7120 was improved by combining epPCR and DNA shuffling.
The best variant, which had one amino acid substitution (N305D),
exhibited a two-fold increase in t1/2 and a 1.87-fold increase in specific
activity compared to the wild-type ana-LOX. The amino acid
Asp305 was confirmed by site-saturation mutagenesis to be crucial
for improving activity and thermostability. The mutant with
enhanced activity and thermostability is potentially useful for food
industry applications. on the directed evolution of the LOX from Anabaena
sp. for improving thermostability and catalytic activity, and the mutant is of potential importance in food
processing and flavor biosynthesis.