KDPG

KDPG is a member of a yet unexplored group of aldolases that utilize pymvate or phosphoenol pymvate as the nucleophile in the aldol addition. They are quite tolerant of different electrophilic components and accept a large number of uimatural aldehydes (148). The reaction itself, however, is quite specific, generating a new stereogenic center at the C-4 position. 

Cheriyan, M., Toone, E.J. and Fierke, C.A. (2007) Mutagenesis of the phosphate-binding pocket of KDPG aldolase enhances selectivity for hydrophobic substrates. Protein Science A Publication of the Protein Society, 16, 2368-2377. 

A. Singly wound parallel /3 barrels Triosephosphate isomerase Pyruvate kinase domain 1 KDPG aldolase ( )... 

The first such case was concerned with the limited substrate acceptance of d-2-keto-3-deoxy-6-phospho-gluconate (KDPG) aldolase (161). This catalyzes the (reversible) reaction of pyruvate (41) to certain chiral aldehydes such as 42, with formation of aldol products such as 43. It was known that this aldolase is highly specific for chir l-phosphorylated aldehydes with the d configuration at the C2 position leading stereoselectively to a precursor of the corresponding d sugar such as 44 (162) ... 

The 2-keto-3-deoxy-6-phosphogluconate aldolase (KDPG aldolase EC 4.1.2.14) catalyzes the cleavage of the dehydration product of 6-phosphogluconate, (KDPG), into glyceraldehyde-3-phosphate and pyruvate in the Entner-Doudoroff pathway (Scheme 7, R = P03H2). This... 

SchBme 7 Reversible aldol addition reaction catalyzed by KDPG and KDG aldolases... 

Table 5 Compared Relative Activities of KDGal Aldolase and KDPG Aldolase Toward Various Acceptors...

The carbon-carbon forming ability of aldolases has been limited in part by their narrow substrate utilization. Site-directed mutagenesis of various enzymes to alter their specificity has most often not produced the desired effect. Directed evolution approaches have furnished novel activities through multiple mutations of residues involved in recognition in no instance has a key catalytic residue been altered while activity is retained. Random mutagenesis resulted in a double mutant of E. coli 2-keto-3-deoxy-6-phosphogluconate (KDPG) aldolase with reduced but measurable enzyme activity and a synthetically useful substrate profile (Wymer, 2001). 

Redesign of an Enzyme s Active Site KDPG Aldolase 331 11.5 Comparison of Directed Evolution Techniques 331... 

Scheme 5.37. Compounds synthesized on a preparative scale utilizing KDPG aldolase.

Scheme 5.39. Alteration of the acceptor enantioselectivity and phosphate dependency by directed evolution of KDPG aldolase.

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