Hemoglobin is the protein in red blood cells that carries oxygen. This protein is composed of two parts: globin and heme, the part that contains all of the iron of hemoglobin. Heme has the following composition: 66.24% C, 5.23% H, 9.06% Fe, 9.09% N, and 10.38% O. Assuming one Fe atom per heme, obtain its molecular mass. The molecular mass of hemoglobin is approximately 64,500 amu. The hemoglobin molecule contains four globin units and four heme units. What is the approximate molecular mass of globin?.