Selection with transition-state analogues

Recognition of this fundamental feature of enzymes has led to the design of transition-state analogues (TSA) as potent inhibitors of enzymes and to their use as haptens to induce the immune system into generating antibodies endowed with catalytic ac- 

Selection by affinity chromatography on a transition-state analogue has also been used to extract active enzymes from a library of phage-displayed GST Al-1 mutants. Four residues in the electrophilic substrate binding site were randomly mu- 

In these two examples, the principle of transition-state stabilization as a source of enzymatic catalysis is successfully exploited for the selection of active mutants. Selection with a TSA appears to be able to enrich libraries in variants with high catalytic activity. 

Selection with transition-state analogues has also been used to extract catalytic antibodies from libraries of phage-antibodies. McCafFerty et al. [52] have shown that antibodies with nanomolar affinities for a phosphonate transition-state analogue could easily be extracted from a library derived from immunized mice. 

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Fig. 5.4. Phage-displayed glutathione-S-transferase mutants were selected with an immobilised transition-state analogue [51].

Antibodies possessing glycosidase activity have been induced by immunization of mice with conjugates of the transition-state analogue 21 (Fig. 5.10A). A combinatorial phage-Fab library was then constructed by PCR amplification of the heavy and light chains. Selection with a BSA-conjugated suicide inhibitor 22 (Fig. 5.10B) was then... 

A similar approach was employed in our laboratory for the development of molecularly imprinted catalysts for the enantio-selective reduction of prochiral ketones with borane (CBS reaction) [122]. A stable, polymerisable transition state analogue of this reaction leading to the formation of one particular enantiomer product was prepared (Fig. 4.9). After polymerisation, the template molecule can... 

Hammock and co-workers (Hammock et ai, 1982 Abdel-Aal, 1984 Prestwich et ai, 1984) prepared several 3-alkylthio-l,l,l-trifluoro-2-propanones with juvenile hormone-like side chains. These compounds were designed as possible transition-state analogue inhibitors of JH esterases. The most active analogue (78) showed a dose-dependent delay in pupation and a selective inhibition of JH esterase of the cabbage looper, Trichopltisia ni. 

Ohkubo, K. Sawakuma, K. Sagawa, T. Shape-and stereo-selective esterase activities of cross-linked pol mers imprinted with a transition-state analogue for the hydrolysis of amino acid esters. J. Mol. Catal. A Chem. 2001,165, 1-7. 

A -Protected a-aminoalkyl-//-phosphinic acids (857) were found to be novel practical building blocks in three-component Mannich-type A -phosphonomethylation condensations with formaldehyde (858) and secondary amine/amino acids (859). This reaction led to multifunctional phosphinic pseudodipeptides (860), designed to act as extended transition state analogue inhibitors of selected cytosolic leucine and microsomal alanyl aminopeptidases (Scheme 215). ... 

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