1.14.99.58	additional information	heme transfer to the enzyme is independent of heme affinity and is mediated via a specific protein-protein interaction. A spin transition is involved during the transfer process with spin-state crossover occuring in the heme binding protein PhuS prior to the heme transfer step or alternatively occuring within the enzyme. Activation energies at pH 7.5 for the heme transfer from PhuS to enzyme are about 12-14 kcal per mol	678146