(A) Fisher projection of L-threonine and L-allo-threonine structures. The nomenclature of threo and erythro configurations is derived
from the diastereomeric aldoses threose and erythrose, on which L-threonine and L-allo-threonine can be superimposed, respectively. (B)
Three-dimensional PYMOL stick representation of L-threonine and L-allo-threonine as they are actually oriented in the eTA–Thr structure
(Fig. 6B), showing that, at the enzyme active site, the difference between the two diasteroisomers is found only in the position of the
methyl group bound to the b-carbon. The figure also clearly shows a periplanar conformation of the Oc–H bond with respect to the Ca–Cb
bond, as present in the enzyme-bound hydroxyamino acids. This periplanar conformation is stereochemically required by the retro-aldol
cleavage mechanism (Scheme 1
(A) Fisher projection of L-threonine and L-allo-threonine structures. The nomenclature of threo and erythro configurations is derived
from the diastereomeric aldoses threose and erythrose, on which L-threonine and L-allo-threonine can be superimposed, respectively. (B)
Three-dimensional PYMOL stick representation of L-threonine and L-allo-threonine as they are actually oriented in the eTA–Thr structure
(Fig. 6B), showing that, at the enzyme active site, the difference between the two diasteroisomers is found only in the position of the
methyl group bound to the b-carbon. The figure also clearly shows a periplanar conformation of the Oc–H bond with respect to the Ca–Cb
bond, as present in the enzyme-bound hydroxyamino acids. This periplanar conformation is stereochemically required by the retro-aldol
cleavage mechanism (Scheme 1
การแปล กรุณารอสักครู่..