Synthetic enzyme development

The complexity of today s pharmaceutical compounds and an increasing awareness of the environmental impact of traditional chemical syntheses have opened the door to biocatalysis. Directed evolution is an integral tool in the development of synthetic enzymes, ensuring they are suitable for use in an industrial setting. The past success of this approach indicates that it will continue to provide many examples of safe and efficient production of chemical intermediates and medical compounds. 

Riley, D.P. Rational design of synthetic enzymes and their potential utility as human pharmaceuticals development of manganese(II)-based superoxide dismutase mimics. Adv. Supramol. Chem. 2000, 6, 217-244. 

The development of synthetic enzymes and proteins has also been achieved through the preparation of structurally defined peptide nanostructures. A nice example, reported by DeGrado and co workers [67], is the construction (Fig. 27) of a four a-helix bundle system (72) that was shown to complex four metalloporphyrins by their axial coordination with the imidazole of the properly oriented histidines. This type of structure could be used as an artificial photosynthetic center. Along the same lines, Benson and co-workers [68] recently prepared a miniature hemoprotein, 73, by linking two units of a 13-amino acid peptide to a porphyrin. UV-visible and CD studies confirmed that the metalloporphyrin is indeed sandwiched between the a-helical peptides, as depicted in 73. 

Because the reaction is degradative, it requires a starch chain, and the product of a single event is a-Glc 1-P and a starch chain that has had one or more glucosyl residues removed. It is, therefore, not surprising that the reaction in the reverse synthetic direction also requires a starch chain or so-called primer. The primer hypothesis for the synthesis of polysaccharide was, thus, developed from an enzyme that was actually a degradative enzyme and not a synthetic enzyme. Nevertheless, the primer-dependent mechanism has been incorrectly assumed for the biosynthesis of starch for over 60 years. 

Based on these mechanisms a new frontier in the application of enzymes to biotechnology, including the development of synthetic enzymes (synzymes)82,83 will be exploited. Research on structure-function relationships between ribozymes and abzymes will lead to the development of a number of sequence specific catalysts, which will control expression of a specific gene or its products, and eventually to application as pathogen controls in agriculture and to clinical use. Sequence specific abzymes may also facilitate research on the primary structure determination of protein. 

Ma Y, Stern RJ, Scherman MS, Vissa VD, Yan W, Jones VC, Zhang F, Franzblau SG, Lewis WH, Mcneil MR. Drug targeting Mycobacterium tuberculosis cell wall synthesis genetics of dTDP-rhamnose synthetic enzymes and development of a microtiter plate-based screen for inhibitors of conversion of dTDP-glucose to dTDP-rhamnose. Antimicrob. Agents Chemother. 2001 1407-1416. 

The promise of fixed enzymes to process many food and waste products is only just beginning to be realized [84]. Combining this technology with the developing field of synthetic enzyme preparations will lead to a wide range of feasible, clean, and specific chemical conversions never before thought to be possible [85]. 

RATIONAL DESIGN OF SYNTHETIC ENZYMES AND THEIR POTENTIAL UTILITY AS HUMAN PHARMACEUTICALS DEVELOPMENT OF MANGANESEdD-BASED SUPEROXIDE DISMUTASE MIMICS Dennis P. Riley... 

The possibility to tailor-make MIPs towards a desired selectivity in combination with the high stability of the materials under a broad range of conditions has rendered MIPs attractive for the development of synthetic enzymes [243, 244]. A popular strategy has been to imprint a transition state analog to obtain a polymer that reduces the activation energy of the reaction. Catalytically active groups are often included in the polymer network. This approach has been applied towards ester and amide hydrolysis reactions [245, 246]. Examples of other reactions where MIPs have been utilized as enzyme mimics are isomerization [247], transamination [248], Diels-Alder reaction [249], 3-elimination [250] and regioselective cycloaddition [251]. 

The possibility that an enzyme could be assembled entirely by chemical methods is not new and was first raised by Emil Fischer in a note to his contemporary Adolf Bayer in 1905 My entire yearning is directed toward the first synthetic enzyme. If its preparation falls into my lap with the synthesis of a natural protein material, 1 will consider my mission fulfilled. [199]. While Fisher made important contributions to peptide chemistry culminating in the synthesis of an 18-mer peptide [4], his dream of enzyme total synthesis went unfulfilled in his lifetime. The synthetic and analytical technologies required to accomphsh this ambitious goal would take decades to develop [58]. 

Besides the incorporation of native enzjones in microgels, the development of synthetic enzymes in which the catalytic... 

Becker et al recently reported a variant of the purine synthetic enzyme phosphoribosylpyrophosphate (PP-ribose-P) synthetase (EC 2.7.6.1) in a patient with symptoms characteristic of the Lesch-Nyhan syndrome at three years of age, but with normal HGPRT enzyme levels. The clinical manifestations of this X-linked disorder in three previous families in which it had been described had been restricted to gout, uric acid lithiasis and/or renal insufficiency and had not developed until early adulthood. ... 

With the most advanced streptavidin variants, the strategy in which a racemic catalyst is converted to a chiral-at-metal complex and then further assisted by residues in the chiral protein has led to the development of both R- and 5-selective synthetic enzymes for imine reduction. Extensive kinetic data has been obtained for these new synthetic enzymes, and computer modelling of the complex stmctures (which contain four interacting subunits) serves to support and understand the results. An induced lock and key where the host protein structure determines the catalyst structure and the reduction selectivity is proposed (Fig. 44) [141]. 

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