Biocatalysis Position In Green Chemistry

Transcription

1 Biocatalysis Position In Green Chemistry How Green is Biocatalysis? To Calculate is To know Yan Ni, Dirk Holtmann and Frank Hollmann ChemcatChem 2014, 6,

2 DEFINITIONS AND CONCEPTS

3 Organic synthesis concept Organic synthesis is concerned with the construction of molecules, involving chemical reactions. Several reactions will take place one after another (or in parallel) until the targeted molecule is complete. A chemical reaction model: + Molecule 1 Molecule 2 = Molecule 34 3 Molecule 3 + = Molecule 5 Molecule 6

4 Example Boot s process for ibuprofen (analgesic like aspirin) synthesis (1960) : 6 steps and numerous non recyclable waste.

5 1990 Green Chemistry Reduce the impact of chemistry on the environment by preventing pollution at its source and using fewer natural resources U.S. Environmental Protection Agency (EPA) Green chemistry efficiently utilizes (preferably renewable) raw materials, eliminates waste and avoids the use of toxic and/or hazardous reagents and solvents in the manufacture and application of chemical products principles of green chemistry by P. Anasta and J. Warner 2007 REACH European rules : to secure production and utilisation of chemicals

6 12 principles of Green Chemistry Non-toxic substances Atom economy Catalysts Avoid auxiliary substances Green Chemistry Efficient production Innocuous degradation products Preventing waste Avoid derivatisations Diminishing accidents Real time measurement Renewable feedstock Save energy

7 Example «Green process» New process by BHC (1990): only 3 steps and only one sub-product (acetic acid) which is recycled for another use.

8 Biocatalysis "The vast number of chemical reactions taking part in a living cell are controlled by organic catalysts. Life is the orchestrated combination of processes catalyzed by enzymes." WILLSTÄTTER RICHARD - ( ) Nobel price in 1915 chlorophyll and other plant pigments Biocatalysis may be broadly defined as the use of enzymes or whole cells as biocatalysts for industrial or academic synthetic chemistry.

9 Nature, a molecule architect? Enzyme ubiquity and diversity Escherichia coli Human 4500 genes 1518 enzymes 1700 reactions ~ genes ~ proteins ~ enzymes

10 Nature, a molecule architect? Prokaryotic cell Eukaryotic cell

11 Orchestration? Metabolic map

12

13 Huge diversity of natural Compounds and reactions

14 How this can work? CHEMOSELECTIVITY, REGIOSELECTIVITY, STEREOSELECTIVITY An average protein would contain 300 aa and as 20 proteinogenic amino acids exist, ( ) different polymers are theoretically possible The complete Universe is insufficient to contain a copy of each protein. An enzyme is thus able to bind a substrate specifically to lead to a chemical reaction. To give an idea: our Universe would contain atoms in the eye accessible part Enzymes are chemoselective, regioselective and stereoselective Chemoselectivity: reaction on a polyfunctional molecule possible without any protection. Regioselectivity: Identical functional groups distinguished depending on their position on the molecule. Stereoselectivity: enzymes are chiral catalysts. They are able to differentiate stereoisomers and in particular enantiomers.

15 From gene to protein

16 From gene to protein

17 Enzymes are proteins Proteins are polymers (macromolecules) built up from amino acids. Amino acids Dipeptide Oligopeptide Protein Organisation and folding of this chain lead to a 3D structure.

18 Enzymes are proteins cristal Cartoon representation Soybean protein

19 Enzymes at work They «cut» molecular assemblies into smaller molecules = + They «stick» for constructing molecular assemblies + =

20 Enzymes at work Key and lock concept

21 Enzymes at work

22 Enzymes at work Rate factor increase from 10 7 to depending on the enzyme

23 Enzymes production How industrial enzymes are made? And in the lab?

24 How enzymes are used? In water, buffer, low temperature, mild conditions However Enzymes are denatured by a change in temperature, ph or chemical action inactive

25 APPLICATIONS Detergent, food, pharmaceutical, chemical and leather industries are producing and/or using enzymes

26 Industrial synthesis, artificial aroma In food? Vanillin (From lignin)

27 Enzymes at home?

28 Amylase

29 Cellulase

30 Protease

31 In cars? Bioethanol CELL FACTORIES Microorganisms Tailored to the Raw Materials Available Ethanol is produced from non-food biomass such as farming and forest waste, green waste and dedicated crops. This involves extracting the cell wall (cellulosic) sugar from biomass utilizing enzymes that convert cellulose into sugar (glucose) through hydrolysis. Then yeast strains convert the sugars into ethanol via fermentation. The resultant ethanol is distilled to ensure it is of suitable quality for use as biofuel. For this biotechnology process to be profitable, more efficient enzymes are needed, which is a core focus of R&D in this area

32 Categories of chemicals produced by cell factories

33 ow to get efficient desired enzymes? Biodiversity De novo design (computer modelling) Directed evolution of existing enzymes Efficient biocatalysts for fine green chemistry or industrial chemistry

34 Directed evolution Desired biocatalyst?? Wild-type biocatalyst

35 Directed evolution NEW GENES => NEW ENZYMES WITH NEW PROPERTIES => SCREENING Molecular biology Evolution Screening

36 From biodivsersity Harvest the DNA (genes) from the environment Databases Screening for the desired properties New enzymes (list of databases)

37 CONCLUSION

38 12 principles of Green Chemistry Non-toxic substances Atom economy Catalysts Avoid auxiliary substances Green Chemistry Efficient production Innocuous degradation products Preventing waste Avoid derivatisations Diminishing accidents Real time measurement Renewable feedstock Save energy

39 BIOCATALYSIS HAS A PRIVILEGED POSITION IN GREEN CHEMISTRY!