Originally a biologist who got his doctorate from the Sorbonne in Paris, Zalkind took part in the October Revolution on the side of Leon Trotsky. When Trotsky 1917 became People's Commissar for Foreign Affairs (de facto: Soviet foreign minister), he made Zalkind his first deputy (de facto: Permanent Under Secretary of State or Deputy Minister of Foreign Affairs).[4][5][6][7][8] When Trotsky resigned as foreign minister (because of the peace Treaty of Brest-Litovsk), Zalkind was sent as plenipotentiary and consul to Switzerland[3][9][10][11][12] (Zürich, 1918), Turkey (Istanbul, 1922), Latvia (Liepāja, 1923) and Italy (Genoa, 1924, and Milan, 1925). Back in the Soviet Union, after Trotsky's downfall he was expelled from the Communist party and shot himself.[3]