SPECIFICITY OF CLASS I TAGATOSE 1,6-BISPHOSPHATE ALDOLASE ENHANCED TOWARD TAGATOSE 1,6-BISPHOPHATE

Class I tagatose 1,6-bisphosphate aldolase catalyzes the reversible condensation of dihydroxyacetone phosphate and glyceraldehyde 3-phosphate to produce four D-ketohexoses 1,6-bisphosphate: D-tagatose 1,6-bisphosphate, D-fructose 1,6-bisphosphate, D-psicose 1,6-bisphosphate and D-sorbose 1,6-bisphosphate. These four sugars are diastereoisomers and differs from each other in their stereochemistry at carbons 3 and 4.
The structure determination of three class I tagatose 1,6-bisphosphate aldolases has afforded new insight into their catalytic mechanism as well as their evolution. However, the determinant(s) that allow(s) the enzyme to be so unspecific at carbon 4 have remains unknown.
The aim of this project is focused on the characterization of the structural features of tagatose 1,6-bisphosphate aldolases that determine the specificity of the enzyme towards tagatose versus fructose 1,6-bisphosphate (carbon C4).