Inhibitory activities of the heterotrimers formed from two α-type phospholipase A2 inhibitory proteins with different enzyme affinities and importance of the intersubunit electrostatic interaction in trimer formation

►Trimer formation of PLIα occurs only among the subunits having the same α-helical neck region. ►The inhibitory activity of PLIα trimer is determined by one subunit with the highest activity and not affected by the number of the subunit with the high activity. ►The intermolecular electrostatic interactions between Glu23 and Lys28 of GbPLIα are responsible for the stability of its trimeric structure.