Human Apolipoprotein A1 protein, His tag

Apolipoprotein A1 (APOA1) is the major protein component of HDL particles in plasma. It is a cofactor for lecithin cholesterolacyltransferase (LCAT) which is responsible for the formation of most plasma cholesteryl esters. ApoA1 was also isolated as a prostacyclin (PGI2) stabilizing factor, and thus may have an anticlotting effect. ApoA1 is often used as a biomarker for prediction of cardiovascular diseases. Besides, Haptoglobin (Hpt) has been identified as an interactor of APOA1, thus a binding ELISA assay was conducted to detect the interaction of recombinant human APOA1 and recombinant human Hpt. Briefly, APOA1 were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to Hpt-coated microtiter wells and incubated for 2h at 37ºC. Wells were washed with PBST and incubated for 1h with anti-APOA1 pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody, wells were aspirated and washed 3 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37ºC. Finally, add 50 μl stop solution to the wells and read at 450nm immediately. The binding activity of APOA1 and Hpt was in a dose dependent manner.