SEPARATION OF HEMOGLOBIN AND MYOGLOBIN FROM YELLOWFIN TUNA RED MUSCLEBY ULTRAFILTRATION - EFFECT OF PH AND IONIC-STRENGTH

Efficiency and selectivity of 30 and 150 kd inorganic ultrafiltration membranes (Techsep) toward tuna hemoglobin and myoglobin were studied. The influence of pH and ionic strength was investigated. Mass flow of myoglobin was higher at its isoelectric pH (8.6) and for low ionic st rength (1.5 mM). This result was related to the absence of electrostat ic repulsion between myoglobin and the surface of the dynamic membrane . The use of high ionic strength 0.15 MNaCl involved an apparent dimer isation of myoglobin and consequently a lower permeation through the m embrane due to the molecular weight increase. The permeation and reten tion of hemoglobin did not agree with the effect of pH observed with m yoglobin (best permeation at isoelectric pH) but followed the behavior of myoglobin. This was explained by a myoglobin concentration 10 time s higher than hemoglobin concentration. The yield of retention selecti vity was investigated. Selectivity of the membrane at pH 8.6 and 1.5 m M was favorable to myoglobin (increase of 40%) whereas a reversed sele ctivity was observed at pH 7.3, 0.15 M. (C) 1996 John Wiley & Sons, In c.