Observations on the binding of haemoglobin and haematin by serum proteins in the rabbit. rat and guinea pig.

When haemoglobin is added to human plasma, it is bound through the globin portion of the molecule to an C2-globulin (Jayle, Boussier & Badin, 1952; Nyman, 1959). It has also been suggested that in human sera haemoglobin combines with albumin (Neale, Aber & Northam, 1958) and with a Plglobulin (Neale et al. 1958; Tombs, 1960), but these complexes could not be found by Allison & ap Rees (1957), Aber & Rowe (1960) or Nyman (1960). Liang (1957) investigated the haemoglobinbinding properties of various animal plasmas and claimed that haemoglobin was bound by an oc2globulin in the horse, dog, pig and duck, by albumin in the turtle, by fibrinogen in the ox, and by both an oc2-globulin and albumin in the frog. In humans, the reaction between alkaline haematin and plasma proteins differs from that between haemoglobin and plasma protein. Heilmeyer (1933) was the first to suggest that a reaction took place between alkaline haematin and plasma proteins; Fairley (1938, 1941) showed that the reaction was between haematin and serum albumin and he termed the complex methaemalbumin. On electrophoresis, methaemalbumin migrates at the same rate as uncombined albumin (Fiser-Herman & Davorin, 1953). Other complexes besides 'haematin-albumin' have been described, but there is not complete agreement as to their rate of migration on paper electrophoresis. Fiser-Herman & Davorin (1953) describe a haematin-protein complex migrating in the M2-globulin region; on the other hand, Neale et al. (1958), Aber & Rowe (1960) and Nyman (1960) have all described a haematinprotein complex travelling in the a-globulin. Moreover, Aber & Rowe (1960), using the technique of free-solution electrophoresis, also found haematin-protein complexes migrating in the aC2and y-globulin regions. The reaction between alkaline haematin and animal plasma proteins has also been investigated. Fairley (1941) found that a complex was formed between rabbit albumin and alkaline haematin, although this complex did not give the characteristic absorption spectrum of human and simian methaemalbumin. Fiser-Herman & Davorin (1953), using paper electrophoresis, found haematinprotein complexes migrating in the albumin and in the oc2-globulin region in monkey plasma (Macacun rhesus); in the cow and horse they found a complex migrating in the albumin region, in the pig a complex migrated in the aand P-globulin region, and in the chicken there were complexes in the albumin and oc-globulin region. Further observations are presented here on the binding of both haemoglobin and alkaline haematin by plasma proteins obtained from the rabbit, rat and guinea pig. The investigations were made with the technique of electrophoresis on cellulose acetate paper. METHODS