Ac. Joerger et al., Catalytic action of fuculose 1-phosphate aldolase (class II) as derived from structure-directed mutagenesis, BIOCHEM, 39(20), 2000, pp. 6033-6041
Previous analyses established the structures of unligated L-fuculose 1-phos
phate aldolase and of the enzyme ligated with an inhibitor mimicking the su
bstrate dihydroxyacetone phosphate. These data allowed us to suggest a cata
lytic mechanism. On the basis of this proposal, numerous mutations were now
introduced at the active center and tested with respect to their catalytic
rates and their product distributions. For several mutants, the structures
were determined. The results demonstrate the catalytic importance of some
particular residues in defined conformations and in the mobile C-terminal c
hain end. Moreover, they led to a modification of the proposed mechanism. T
he effect of some mutations on enantioselectivity and on the ratio of diast
ereomer formation indicates clearly the binding site of the aldehyde moiety
in relation to the other substrate dihydroxyacetone phosphate.