Page 189 - Cascade_Biocatalysis_Integrating_Stereoselective_and_Environmentally_Friendly_Reactions

7.2 Dihydropyrimidinase 165

Bimetallic
center

(a)

(b)
Figure 7.3 (a) SmelDhp crystal grown in arrangement of SmelDhp as observed
microcapillaries by the counter diffusion by X-ray crystallography [40, 42]. (Source:
technique (left) and its monomeric structure Mart´ ınez-Rodr´ ıguez, S. et al. 2010 [42],
showing the catalytic bi-nuclear Zn center Fig. 2, p. 202. Reproduced with permission
(right), PDB ID 3DC8. (b) Native tetrameric of Elsevier.)

735, and Rhizobium sp. NA04-01 suggest the opposite enantioselectivity [28]. On the
2
other hand, studies with 5-monosubstituted DHUs (precursors of β -amino acids)
are less common. As far as we know, only SmelDhp has been studied in this respect
with 5-methyl- and 5-phenyl-DHU as substrates. Though the enzyme hydrolyzed
totally a racemic mixture of both compounds, a preference toward one of the
enantiomers of 5-phenyl-DHU could be inferred from the progression curves [44].