Donald F. Turner, 73, an economics scholar who headed the Justice Department's antitrust division during the Johnson Administration. President Lyndon B. Johnson appointed Turner as assistant attorney general in charge of antitrust in 1965. Early in his career, Turner and Carl Kaysen wrote "Antitrust Policy," an analysis of U.S. antitrust law widely regarded as a classic in its field. Turner, a native of Chippewa Falls, Wis., graduated from Northwestern University in 1941. He received a doctorate in economics from Harvard University in 1947 and a law degree from Yale University in 1950. After a clerkship with Supreme Court Justice Tom Clark and a brief period of law practice, Turner joined the Harvard Law School faculty in 1954 and retired in 1979. After leaving Harvard, Turner joined the Washington law firm of Wilmer Cutler & Pickering, served as visiting professor at Georgetown University Law Center and was a fellow at the Brookings Institution. In Washington on Tuesday of the complications of Alzheimer's disease.