Hemoglobin St Luke's or α295Arg (G2) β2.

A new hemoglobin variant, designated hemoglobin-St Luke's. was detected by routine starch-gel electrophoresis in four members of a Maltese family. The carriers of this abnormality are clinically and hematologically normal. Structural analyses showed the replacement of prolyl residue in position 95 (G2) of the alpha chain by an arginyl residue. The relative amount of hemoglobin-St Luke's present in the red cell hemolysates of its cagier is approximately 10 %, compared to about 23 % for hemoglobin-G Georgia and 15% for hemoglobin Rampa (the other two variant in which prolyl residue α95 (G2) is replaced). Sedimentation velocity studies of hemoglobin. St Luke's in NaCl solutions of increasing concentration up to 2 M indicate that the oxy derivative is extensively dissociated into dimers in 0.1 M NaCl at neutral pH; whereas under the same conditions, the deoxygenated molecule retains a tetrameric structure. In the deoxy state, appreciable tetramer formation occurs even in 2 M NaCl. In addition, association-dissociation in oxyor cyanferrihemoglobin St Luke's is troth pH and temperature dependent. [ABSTRACT FROM AUTHOR]