Overview of Biocatalysis in Green Chemistry

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Overview of Biocatalysis in Green Chemistry

• Steve S.-F. Yu
• Institute of Chemistry, Academia Sinica
• ???,??????????
• B601?
• Tel [phone]
• sfyu_at_chem.sinica.edu.tw
• Sow Choo University
• March 25th, 2009

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• The Definition of Biocatalysis
• Green Chemistry vs. Biocatalysis
• Whole Cell Biocatalysis Fermentation
• Bio-related Energy Conversion vs. Biofuel

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The Definition of Biocatalysis

• The employment of enzymes and whole cells have
  been important for many industries for centuries.
  The most obvious usages have been in the food and
  drink businesses where the production of wine,
  beer, cheese etc. is dependent on the effects of
  the microorganisms.
• More than one hundred years ago, biocatalysis was
  employed to do chemical transformations on
  non-natural man-made organic compounds, and the
  last 30 years have seen a substantial increase in
  the application of biocatalysis to produce fine
  chemicals, especially for the pharmaceutical
  industry.

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Levels of Organization

• Atoms
• Molecules and macromolecules
• Cells
• Tissues
• Organs
• Organism
• Population
• Community
• Ecosystem
• Biosphere

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Figure 1.8Molecular organization in the cell is
a hierarchy.
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Central Dogma
DNA
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Replication
Reverse Transcription
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Transcription
RNA
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Translation
Protein
Juang RH (2004) BCbasics
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Seven Characteristics of Life

• Cells and organization
• Energy use and metabolism
• Response to environmental changes
• Regulation and homeostasis
• Growth and development
• Reproduction
• Biological evolution

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Whole cells

• Many complicated chemical conversion process.
• Many side reaction may occurred.
• It is not required with cofactor recycling and
  usually exhibit relatively higher activities.
• However, it may require expensive equipment,
  tedious workup, delicate control of the
  metabolism details.

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Isolated Enzymes

• Fewer steps for chemical conversion
• Less side reaction
• Isolated enzymes can behave in any form such as
  in aqueous solution, organic solvents (reduction
  of activity low) and immobilied (hard to maintain
  its activity via immobilization).
• However, it is required the cofactor recycling,
  less reactivity towards lipophilic substrates.

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Advantages of Biocatalysts using Enzymes

• Enzymes are very efficient Bocatalysis
• Enzymes are environmentally acceptable.
• Enzymes act under mild conditions.
• pH 5-8, 20-40?C
• Enzymes are compatible with each other. (no side
  reaction)
• The conversions are carried out in aqueous
  solution

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Disadvantage

• Enzymes are provided by Nature in only one
  enantiomeric form.
• Enzyme require narrow operation parameters.
• Enzymes display their highest catalytic activity
  in water.
• Enzymes are bound to their natural cofactors.
• Enzymes are prone to inhibition phenomena.
• Enzymes may cause allergies.

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12 Principles of Green Chemistry

• 1. PreventionIt is better to prevent waste than
  to treat or clean up waste after it has been
  created.
• 2. Atom EconomySynthetic methods should be
  designed to maximize the incorporation of all
  materials used in the process into the final
  product.
• 3. Less Hazardous Chemical SynthesesWherever
  practicable, synthetic methods should be designed
  to use and generate substances that possess
  little or no toxicity to human health and the
  environment.

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12 Principles of Green Chemistry

• 4. Designing Safer ChemicalsChemical products
  should be designed to effect their desired
  function while minimizing their toxicity.
• 5. Safer Solvents and AuxiliariesThe use of
  auxiliary substances (e.g., solvents, separation
  agents, etc.) should be made unnecessary wherever
  possible and innocuous when used.
• 6. Design for Energy EfficiencyEnergy
  requirements of chemical processes should be
  recognized for their environmental and economic
  impacts and should be minimized. If possible,
  synthetic methods should be conducted at ambient
  temperature and pressure.

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12 Principles of Green Chemistry

• 7. Use of Renewable FeedstocksA raw material or
  feedstock should be renewable rather than
  depleting whenever technically and economically
  practicable.
• 8. Reduce DerivativesUnnecessary derivatization
  (use of blocking groups, protection/
  deprotection, temporary modification of
  physical/chemical processes) should be minimized
  or avoided if possible, because such steps
  require additional reagents and can generate
  waste.
• 9. CatalysisCatalytic reagents (as selective as
  possible) are superior to stoichiometric
  reagents.

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12 Principles of Green Chemistry

• 10. Design for DegradationChemical products
  should be designed so that at the end of their
  function they break down into innocuous
  degradation products and do not persist in the
  environment.
• 11. Real-time analysis for Pollution
  PreventionAnalytical methodologies need to be
  further developed to allow for real-time,
  in-process monitoring and control prior to the
  formation of hazardous substances.
• 12. Inherently Safer Chemistry for Accident
  Prevention Substances and the form of a
  substance used in a chemical process should be
  chosen to minimize the potential for chemical
  accidents, including releases, explosions, and
  fires.

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The Sun is Energy for Life

• Phototrophs use light to drive synthesis of
  organic molecules
• Heterotrophs use these as building blocks
• CO2, O2, and H2O are recycled
• See Figure 17.3

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Figure 17.3The flow of energy in the biosphere
is coupled primarily to the carbon and oxygen
cycles.
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How Do Anabolic and Catabolic Processes Form the
Core of Metabolism Pathways?

• Metabolism consists of catabolism and anabolism
• Catabolism degradative pathways
• Usually energy-yielding!
• Anabolism biosynthetic pathways
• energy-requiring!

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A comparison of state of reduction of carbon
atoms in biomolecules.
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Fermentation

• French chemist Louis Pasteur was the first
  zymologist, when in 1857 he connected yeast to
  fermentation.

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Fermentation

• The German Eduard Buchner, winner of the 1907
  Nobel Prize in chemistry, later determined that
  fermentation was actually caused by a yeast
  secretion that he termed zymase.

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• The research efforts undertaken by the Danish
  Carlsberg scientists greatly accelerated the gain
  of knowledge about yeast and brewing.

Beer fermenting at a brewery.
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Fermentor is easy to be used to control the
bioorganism growth and fermentation process.
Industrial fermentation Though fermentation can
have stricter definitions, when speaking of it in
Industrial fermentation, it more loosely refers
to the breakdown of organic substances and
re-assembley into other substances.
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Commercially Important Fermentation

• Microbial cells or Biomass as the product Eg.
  Bakers Yeast, Lactic acid bacillus, Bacillus sp.
• Microbial Enzymes Catalase, Amylase, Protease,
  Pectinase, Glucose isomerase, Cellulase,
  Hemicellulase, Lipase, Lactase, Streptokinase
  etc.
• Microbial metabolites 
• Primary metabolites Ethanol, Citric acid,
  Glutamic acid, Lysine, Vitamins, Polysaccharides
  etc.
• Secondary metabolites All antibiotic
  fermentation
• Recombinant products  Insulin, HBV, Interferon,
  GCSF, Streptokinase
• Biotransformations Eg. Phenyl acetyl
  carbinol,Steroid Biotransformation

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• ????(alcoholic fermentation)

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C6H12O6 ? 2C2H5OH 2CO2 2 ATP (Energy
Released118 kJ mol-1)
Below the sugar will be glucose (C6H12O6) the
simplest sugar, and the product will be ethanol
(2C2H5OH). This is one of the fermentation
reactions carried out by yeast, and is used in
food production.
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The Structure of Glucose and Ethanol
Ethanol
Glucose
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Anaerobes, Faculative anaerobes and obligate
aerobes

• Faculative anaerobes (organisms that can
  survive in either oxygenated or deoxygenated
  environments and can switch between cellular
  respiration or fermentation, respectively) and
  obligate (strict) aerobes (organisms that can
  survive only with oxygen) have special enzymes
  (superoxide dimutase and catalase) that can
  safely handle these products and transform them
  into harmless water and diatomic oxygen in the
  following reactions
• 1. 2O2- 2H ---Superoxide Dismutase--gt H2O2
  (hydrogen peroxide) O2
• The hydrogen peroxide produced is then
  transferred to a second reaction...
• 2. 2H2O2 ---Catalase--gt 2H2O O2

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Aerobic respiration
C6H12O6 (aq) 6O2 (g) ? 6CO2 (g) 6H2O (l)

?Hc -2880 kJ
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Figure 18.1The glycolytic pathway.
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Figure 19.4The tricarboxylic acid cycle.
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Anaerobic respiration

• In organisms which use glycolysis, the absence
  of oxygen prevents pyruvate from being
  metabolised to CO2 and water via the citric acid
  cycle and the electron transport chain (which
  relies on O2) does not function. Fermentation
  does not yield more energy than that already
  obtained from glycolysis (2 ATPs) but serves to
  regenerate NAD so glycolysis can continue.
  Various end products can also be created, such as
  lactate or ethanol.

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Pyruvate reduction to ethanol in yeast provides a
means for regenerating NAD consumed in the
glyceraldehyde-3-P dehydrogenase reaction.
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Discovering Enzyme
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http//www.besc.org.tw/biomass/m201.htm
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Free Energy

• Hypothetical quantity - allows chemists to asses
  whether reactions will occur
• G H - TS
• For any process at constant P and T
• ?G ?H - T?S
• If ?G 0, reaction is at equilibrium
• If ?G lt 0, reaction proceeds as written

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Figure 3.9The triphosphate chain of ATP contains
two pyrophosphate linkages, both of which release
large amounts of energy upon hydrolysis.
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Figure 3.8 The activation energies for phosphoryl
group-transfer reactions (200 to 400 kJ/mol) are
substantially larger than the free energy of
hydrolysis of ATP (-30.5 kJ/mol).
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E. D. Larson, Biofuel Technologies Overview (2007)
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First generation biofuels

• 'First-generation fuels' refer to biofuels made
  from sugar, starch, vegetable oil, or animal fats
  using conventional technology.

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Bioalcohols

• Alcohol fuels are produced by fermentation of
  sugars derived from wheat, corn, sugar beets,
  sugar cane, molasses and any sugar or starch that
  alcoholic beverages can be made from (like potato
  and fruit waste, etc.).

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Biodiesel

• It is produced from oils or fats using
  transesterification and is a liquid similar in
  composition to mineral diesel. Its chemical name
  is fatty acid methyl (or ethyl) ester (FAME).
  Oils are mixed with sodium hydroxide and methanol
  (or ethanol) and the chemical reaction produces
  biodiesel (FAME) and glycerol.

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Transesterification
Fat Triglycerides
53
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Microbial MethaneBiogenic Natural Gas

• Natural gas can also be formed through the
  transformation of organic matter by tiny
  microorganisms.
• such as
• Methanogens, tiny methane producing
  microorganisms, chemically break down organic
  matter to produce methane.

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Methanogens

• are archaea that produce methane as a metabolic
  byproduct in anoxic conditions.

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Microbial MethaneBiogenic Natural Gas

• Livestock, paddy rice farming, and covered vented
  landfill emissions leading to the production of
  atmospheric methane.
• In certain circumstances, however, this methane
  can be trapped underground, recoverable as
  natural gas.

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Landfill Methane
http//www.epa.gov/methane/sources.html
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Second generation biofuels

• Second generation (2G) biofuels use biomass to
  liquid technology, including cellulosic biofuels
  from non food crops.

59
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Third generation biofuel

• Algae fuel, also called oilgae or third
  generation biofuel, is a biofuel from algae.
  Algae are low-input/high-yield (30 times more
  energy per acre than land) feedstocks to produce
  biofuels and algae fuel are biodegradable.

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Diatoms
Cyanobacteria
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Inside the tube photosynthetic bacteria are
making ethanol more efficiently than other forms
of biomass because the cyanobacteria are natural
fermentators.
http//news-info.wustl.edu/asset/page/normal/4954.
html