Alexander Zakin, 87, Russian-born pianist best known for his 37-year collaboration with violinist Isaac Stern. Zakin also played with other leading violinists, including David and Igor Oistrakh and Leonid Kogan, as well as with cellist Gregor Piatigorsky. Born in Siberia, he left the Soviet Union in 1921 to study and perform in Germany and came to the United States in 1940. Zakin performed at the White House under Presidents Dwight D. Eisenhower, John F. Kennedy and Lyndon B. Johnson. On Friday in New York City.