Regulation of liver sea bass pyruvate kinase by temperature, substrates and some metabolic effectors

Pyruvate kinase of sea bass (Dicentrarchus labrax L.) shows positive cooperativity with respect to both substrates PEP and ADP. The temperature is a modulator of this activity, changing KS0.5 and Hill coefficient values for PEP. The enzyme shows alanine and ATP inhibition and F-1,6-P2 activation at 22 degrees C. F-1,6-P2 eliminates the effect of alanine but not that of ATP. These results could indicate a regulation of this enzyme by temperature and possess kinetic properties which are similar to that of L-type mammals.