ERYTHROCRUORIN OF GLOSSOSCOLEX-PAULISTUS (OLIGOCHAETA, GLOSSOSCOLECIDAE) - MODULATION OF OXYGEN-AFFINITY BY SPECIFIC ANTIBODIES

1) The Soret region absorption spectrum of erythrocruorin (ERC) obtain ed from Glossoscolex paulistus, shows that oxy-ERC has a maximum absor ption peak at 416 nm while the deoxy-ERC form has a maximum at 427 nm. 2) In the presence of a specific antiserum (anti-ERC) and of anti-ERC immunoglobulin G raised in rabbits, there is a deviation to low wavel engths in the maximum absorption peak of deoxy-ERC while for the oxy f orm a red-shift is noticed. These shifts accompanied an increased affi nity of the hemeprotein for oxygen, possibly because of changes in the overall macromolecular conformation. 3) A decrease in the oxygen affi nity of erythrocruorin is observed when large amounts of non-specific serum are used. The same effect is observed in the presence of serum a lbumin, probably as a result of non-specific binding between the album in and erythrocruorin. 4) The fluorimetric titration of erythrocruorin with anti-ERC Fab fragments results in a decrease in the intrinsic tr yptophan fluorescence of the hemeprotein, a response indicative of a m odification in the ERC's quaternary structure.