A method for isolating a protein from a cell culture supernatant, the method comprising: (i) Alternative 1: a1) combining a cell culture supernatant comprising the protein with a divalent cation salt under conditions suitable for the precipitation of impurities in the supernatant to produce a primary supernatant comprising the protein; b1) combining the primary supernatant with an aliphatic alcohol under conditions suitable for forming a protein-containing precipitate and isolating the protein-containing precipitate; c1) re-suspending the protein-containing precipitate in a buffer comprising a divalent cation salt under conditions suitable for the precipitation of impurities therefrom to produce a protein-containing solution; and d1) combining the protein-containing solution with an aliphatic alcohol under conditions suitable for forming a purified protein-containing precipitate and isolating the purified protein-containing precipitate; or (ii) Alternative 2: a2) combining a cell culture supernatant comprising the protein with an aliphatic alcohol under conditions suitable for forming a protein-containing precipitate and isolating the protein-containing precipitate; b2) re-suspending the protein-containing precipitate in a buffer comprising a divalent cation salt under conditions suitable for the precipitation of impurities therefrom to produce a protein-containing solution; and c2) combining the protein-containing solution with an aliphatic alcohol under conditions suitable for forming a purified protein-containing precipitate and isolating the purified protein-containing precipitate. (i) Alternative 1: a1) combining a cell culture supernatant comprising the protein with a divalent cation salt under conditions suitable for the precipitation of impurities in the supernatant to produce a primary supernatant comprising the protein; b1) combining the primary supernatant with an aliphatic alcohol under conditions suitable for forming a protein-containing precipitate and isolating the protein-containing precipitate; c1) re-suspending the protein-containing precipitate in a buffer comprising a divalent cation salt under conditions suitable for the precipitation of impurities therefrom to produce a protein-containing solution; and d1) combining the protein-containing solution with an aliphatic alcohol under conditions suitable for forming a purified protein-containing precipitate and isolating the purified protein-containing precipitate; or a1) combining a cell culture supernatant comprising the protein with a divalent cation salt under conditions suitable for the precipitation of impurities in the supernatant to produce a primary supernatant comprising the protein; b1) combining the primary supernatant with an aliphatic alcohol under conditions suitable for forming a protein-containing precipitate and isolating the protein-containing precipitate; c1) re-suspending the protein-containing precipitate in a buffer comprising a divalent cation salt under conditions suitable for the precipitation of impurities therefrom to produce a protein-containing solution; and d1) combining the protein-containing solution with an aliphatic alcohol under conditions suitable for forming a purified protein-containing precipitate and isolating the purified protein-containing precipitate; (ii) Alternative 2: a2) combining a cell culture supernatant comprising the protein with an aliphatic alcohol under conditions suitable for forming a protein-containing precipitate and isolating the protein-containing precipitate; b2) re-suspending the protein-containing precipitate in a buffer comprising a divalent cation salt under conditions suitable for the precipitation of impurities therefrom to produce a protein-containing solution; and c2) combining the protein-containing solution with an aliphatic alcohol under conditions suitable for forming a purified protein-containing precipitate and isolating the purified protein-containing precipitate. a2) combining a cell culture supernatant comprising the protein with an aliphatic alcohol under conditions suitable for forming a protein-containing precipitate and isolating the protein-containing precipitate; b2) re-suspending the protein-containing precipitate in a buffer comprising a divalent cation salt under conditions suitable for the precipitation of impurities therefrom to produce a protein-containing solution; and c2) combining the protein-containing solution with an aliphatic alcohol under conditions suitable for forming a purified protein-containing precipitate and isolating the purified protein-containing precipitate.