Description General description Forms dimers in aqueous solutions with an association constant of 5 × 104 M-1. The association is accompanied by an enhancement of ~35% in α-helical content. Application Apo A-II constitutes ~20% of the protein moiety of high density lipoprotein (HDL). Biochem/physiol Actions Unlike Apo A-I, Apo A-II possesses no activating properties for lectin-cholesterol acyltransferase (LCAT). Furthermore, it was found that Apo A-II inhibits the activation of LCAT by Apo A-I. Physical form Solution in 10 mM ammonium bicarbonate.