IMMOBILIZED APO-MYOGLOBIN, A NEW STABLE REAGENT FOR MEASURING RATES OF HEME DISSOCIATION FROM HEMOGLOBIN

Apo-myoglobin covalently linked on CNBr-activated Sepharose 4B is prop osed as a new heme acceptor for investigating the heme transfer reacti on from hemoproteins. Immobilized apo-myoglobin has the desirable prop erties of an ideal heme acceptor in that it is characterized by a high affinity for ferric heme, a high stability towards denaturation even at physiological temperatures and can be lyophilized for long-term sto rage. The study of heme release from myoglobin at pH 5.0 and 37 degree s C indicates that heme affinity is increased at least 10-fold relativ e to the soluble protein. Experiments with human hemoglobin allowed th e estimation of the heme release rates from both alpha and beta chains and brought out the greater temperature sensitivity of the alpha chai n heme-globin linkage. (C) 1998 Federation of European Biochemical Soc ieties.