Oxygen binding properties of three different hemoglobin genotypes in turbot (Scophthalmus maximus Rafinesque): Effect of temperature and pH

The aim of this study was to investigate the oxygen binding properties of t he turbot (Scophthalmus maximus) hemoglobin polymorphism with special refer ences to pH and temperature. Hemolysate samples from the three hemoglobin g enotypes Hb-l(1/1), Hb-I(1/2) and Hb-I(2/2), were tested at 10, 16 and 19 d egrees C and at pH values 7.2, 7.5 and 7.8 at 100 mm NaCl respectively. Hb- I(2/2) had the highest oxygen affinity at all three temperatures followed b y Hb-I(1/2) and Hb-I(1/1). There was a significant decrease in oxygen affin ity with increasing temperature and increasing pH in the range 10 to 19 deg rees C for all three genotypes. The genotype Hb-I(1/1) had the highest Bohr effect followed by genotype Hb-I(2/2) and Hb-I(1/2). The effect was highes t at 10 degrees C and decreased with temperature. Temperature sensitivity o f the O-2 binding for turbot hemoglobin was low and increased in general wi th increasing pH. It is hypothesised that the low sensitivity hemoglobins m ay be an adaptation to variable temperature conditions in the distribution area of the species.