Studies on chimeric fusion proteins of human aldolase isozymes A and B

Several kinds of fusion proteins between human aldolases A andB were prepared by recombinant DNA technology and their enzymicproperties were examined. AB chimeras, which have aldolase Aat the N-terminal region and aldolase B at the C-terminal region,were scarcely obtained, while BA chimeras were abundant (Kitajimaet al., (1990), J. Biol. Chem., 265, 17493-17498). All the BABchimeras, aldolase A fragments inserted in aldolase B, showedactivity assignable to aldolase B type, which imply an essentialrole of Tyr residue at the C-terminus of aldolase A in the bindingof fructose-l,6-bisphosphate (Fni-1,6-P₂). BAB chimeras alsoshowed reactivity to effectors such as fructose-2,6-bisphosphate(Fru-2,6-P₂) and pyridoxal 5-phosphate (PLP), in a similar mannerto aldolase B. BAB108 has a similarity to the BA108 chimera,but acts differently from other BAB chimeras, suggesting thatits structure around active site looks like that of aldolaseA