1. Biotransformations in organic chemistry

2. History of biotransformations
wine and beer fermentation B.C. Summer, Babylon
bread B. C. Egypt
Industrial production of fine chemicals:
L-Lactic acid USA

3. Biotransformation in chiral separation
Pasteur 1858

4. Industrial production of efedrine
1921
Industrial production of ascorbic acid
1924

5. Biotransformations
tissue cell cultures (plant cells)
whole cells (bacteria, yeast)
immobilized cells
cell extracts
isolated native enzymes
recombinant enzymes
modified/mutated enzymes
stabilized enzymes (cross-linking)
immobilized enzymes/multi-enzyme systems

6. Advantages of enzymatically catalyzed reactions
high reaction specificity
high regioselectivity
high stereoselectivity (enantioselectivity, diastereoselectivity)
good efficiency (high turnover)
mild reaction conditions
environmental friendly (green) processes
For most organic reactions there are some enzymes that efficiently catalyze them; if not, artificial enzymes could be developed by in vitro evolution.
Enzymes catalyze reverse reactions.

7. Disadvantages and problems of biotransformations
sensitivity to harsh reaction conditions (low or high temperatures, pressure, pH, reagents)
high prices of many enzymes
problematic co-factor regeneration (multi-enzyme systems)
low conversions in some reactions (inhibition by the product)
narrow substrate specificity of some enzymes
limited use of non-aqueous solvents
high dilutions (low volume efficiency)
Enzymes only lower activation barrier (accelerate reactions) – they do not influence reaction balance!!!

8. Chirality

9. Enzymes in productions of enantiopure chiral compounds

10. Enzymes

11. Oxidoreductases

12. Oxidoreductases

13. OXIDATIONS

14. REDUCTIONS

16. Stereo- and regiospecific hydroxylation of non-activated CH
peroxidases, monoxygenases

18. Oxidative deaminations/reductive aminations

19. TRANSFERASES OR LIGASES
used mostly for phosphorylations

20. Enzymatic phosphorylations

21.                                                                                                                                                                                                                         
Enzymatic sulfation of saccharides with the regeneration of the PAPS cofactor. left: proposed transition state of the reaction.

22. HYDROLASES – hydrolyses or condensations

23.                                                                                             
Fig. 2. Typical biotransformations with enantioselective amidohydrolases in whole cells of R. equi, A. aurescens and R. globerulus.

28. Dynamic kinetic resolution – enzyme + racemization catalyst

29. Dynamic kinetic resolution – enzyme + racemization reagent

30. Enantioconvergent synthesis

31. R. Lerner, K. Janda and P. Schultz – Scripps
Catalytic antibodies
If one accepts the basic principle that catalytic function results from the selective use of binding energy to stabilize transition states or to destabilize ground states preferentially, then the problem is simplified to one of synthesizing highly selective molecular receptors. While this remains a major challenge for synthetic chemistry, there does exist a biological solution to the problem of molecular recognition. It is a well-known fact in immunochemistry that the immune response can generate an antibody that is complementary to virtually any foreign molecular structure presented to it. The process whereby these selective, high-affinity receptors are generated resembles in many ways the natural evolution of enzymes.
R. Lerner, K. Janda and P. Schultz – Scripps

33. Table 1. A comparison of the evolution of enzymes and antibodies.
exon shuffling
V-D-J rearrangement
gene duplication
batteries of V, D, and J gene elements
accumulation of point
somatic hypermutation
mutations
natural selection
clonal selection
timescale: years
timescale: weeks

34. The generation of immunological diversity by genetic recombination and somatic mutation.

35. Immunization

37. Transesterification
a) Acyl transfer from the ester 6 to the alcohol 7, catalyzed by antibody 21H3, which was generated against the hapten 9; b) modeled structure of the acyl-antibody intermediate based on the X-ray crystal structure of the antibody-hapten 9 complex.

38. Acyl transfer from the ester 2 to the alcohol 1 catalyzed by antibody 13D6.1, which was generated against the phosphonate diester 5;
NMR structure of the Michaelis complex, with 1 shown in blue and 2 in orange.

39. Oxy-Cope rearrangement
Transition-state analogue 19 and the oxy-Cope rearrangement catalyzed by antibody AZ28.
Overlay of the active sites for the germline antibody structures of AZ28 with the hapten 19 (blue) and without hapten (green). The hapten is shown in yellow.

40. Aldolization
a) Broad substrate scope of antibody-catalyzed aldol reactions. The two antibodies have antipodal activities; b) substrate binding pockets for the antibodies 33F12 (left) and 93F3 (right). The light chain is shown in pink and the heavy chain in blue. The active-site lysine residue is also shown.

41. Generation of an aldolase antibody by reactive immunization with the 2-diketone hapten 13.