Human 15-LOX-1 active site mutations alter inhibitor binding and decrease potency.

Area of Science:

• Biochemistry
• Molecular Biology
• Pharmacology

Background:

• Human 15-lipoxygenase-1 (h15-LOX-1) produces lipid mediators involved in diseases like stroke.
• Understanding h15-LOX-1 inhibitor interactions is vital for developing novel stroke therapeutics.
• Current knowledge of inhibitor binding within the h15-LOX-1 active site is limited.

Purpose of the Study:

• To structurally elucidate inhibitor interactions within the h15-LOX-1 active site.
• To identify specific active site residues critical for h15-LOX-1 inhibitor binding.
• To guide the development of next-generation h15-LOX-1 inhibitors.

Main Methods:

• Site-directed mutagenesis was used to generate eight h15-LOX-1 mutants.
• Molecular modeling guided the selection of active site residues for mutation.
• IC50 values and steady-state inhibition kinetics were determined for wild-type and mutant enzymes.

Main Results:

• Four mutants (F414I, F414W, E356Q, L407A) showed altered inhibitor potency compared to wild-type h15-LOX-1.
• The inhibitors ML351 and compound 18 bind to a similar aromatic pocket near F414.
• Subtle differences in binding modes were observed between ML351 and compound 18.

Conclusions:

• Residues F414, E356, and L407 are important for h15-LOX-1 inhibitor binding.
• ML351 and compound 18 exhibit similar but distinct binding interactions within the h15-LOX-1 active site.
• This study provides a structural basis for designing improved h15-LOX-1 inhibitors for stroke treatment.