Purity > 85% as determined by SDS-PAGE. MW: 15kDa. Full Length: 1-101aa. N-terminal 6xHis-tagged. Nostoc ellipsosporum. Its activity in situ is unknown, however it acts as a viral entry inhibitor, inhibiting HIV-1, HIV-2 and simian immunodeficiency virus (and some other viruses such as feline immunodeficiency virus, measles virus and human herpesvirus) infection and replication. It prevents essential interactions between the envelope glycoprotein and target cell receptors by binding to carbohydrates on viral protein gp120 and possibly by other mechanisms as well. Addition to cells must occur before or shortly after virus addition. It also inhibits cell-to-cell fusion, and virus-to-cell and cell-to-cell transmission of a viral infection. Is remarkably stabile; the protein can withstand multiple freeze-thaw cycles, dissolution in organic solvents, treatment with salt, detergent, H2O2 and boiling without significant loss of anti-HIV activity.