History of Enzymes for Undergraduates

1. History of Enzymes

2. Synopsis
 Introduction to origin of Enzymes
 What are Enzymes?
 Enzymes are divided into six major classes
 Kirchoff's Observation
 Discovery of First Enzyme
 Louis Pasteur Conclusion
 Buchner's Contribution
 Sumner's Postulation
 Enzymes and X-ray Crystallography
 Discovery of Ribozyme and Restriction Enzymes

3. Introduction to the origin of
Enzymes
 The earliest known references to enzymes are from ancient texts dealing
with the manufacture of cheeses, breads, and alcoholic beverages, and for
the tenderizing of meats. These processes were known as fermentation.
 Kühne, studying catalysis in yeast extracts, first coined the term ‘‘enzyme’’
(1877). The word derives from the medieval Greek word enzymos, which
relates to the process of leavening bread.
 Today enzymes continue to play key roles in many food and beverage
manufacturing processes and are ingredients in numerous consumer
products, such as laundry detergents (which dissolve protein-based stains
with the help of proteolytic enzymes). Enzymes are also of fundamental
interest in the health sciences, since many disease processes can be linked
to the aberrant activities of one or a few enzymes.

4. What are Enzymes?
Enzymes
Biological
Catalysts
Presents in all
living Cells
Made of Protein
Converts substrates
into products
Remain unchanged
by chemical reaction
Increase the rate of
chemical reaction

5. Enzymes are divided into six major
classes
 Oxidoreductases catalyse oxidation - reduction reactions.
 Transferases catalyse transfer of functional groups from one molecule to
another.
 Hydrolases catalyse hydrolytic cleavage.
 Lyases catalyse removal of a group from or addition of a group to a double
bond, or other cleavages involving electron rearrangement.
 Isomerases catalyse intramolecular rearrangement.
 Ligases catalyse reactions in which two molecules are joined.

6. Kirchoff’s Observation
 1812, The Russian chemist Kirchoff was studying the following conversion
i.e- starch sugar.
 When a suspension of starch was boiled, Kirchoff observed, no change occurred in the
starch.
 When he added a few drops of concentrated acid before boiling the suspension, the
starch broke down to form glucose.
 The acid which clearly facilitated the reaction underwent no change.
 1835, the Swedish Chemist Jons Berzelius provided a name to the process Kirchoff had
observed, “Catalysis”.
in the presence of strong acids

7. Louis Pasteur Conclusion
 In 1850,
 Sugar Alcohol ( Fermentation)
 Louis Pasteur concluded that it is catalysed by “ferments” and these
ferments were inseparable from the structure off living yeast cell, this
view, called vitalism prevailed for decades.
 He wrote that:-
Alcoholic fermentation is an act correlated with the life and organisation of
yeast, cells, not with the death and putrefaction of the cells.
Yeast

8. DISCOVERY OF FIRST ENZYMES
 By the late 17th and early 18th centuries:-
 Digestion of meat by stomach secretions
 Starch Sugar
(By plant extracts and saliva)
 French chemist Anselme Payen was the first to discover an enzymes,
diastase, in 1833.
 It was extracted from malt solution.

9. Buchner's Contribution
Eduard Buchner
submitted his first
paper on the study
of yeast extracts in
1897.
1
1897: Eduard
Buchner using the
‘‘pressed juice” from
rehydrated dried
yeast demonstrated
that alcoholic
fermentation could
be performed in the
absence of living
yeast cells.
2
He named the
enzymes that
brought about the
fermentation of
sucrose “ Zymase”.
3
In 1907, he
received Nobel Prize
in Chemistry for his
“Discovery of Cell-
Free Fermentation”.
4

10. Sumner's Postulation
 In 1926, James B. Sumner showed that the enzymes urease are use was a
pure protein and crystallized it from jackbean.
 His work made him earn Noble Prize in 1947.
 Sumner found that urease crystals consisted entirely of protein and he
postulated that all enzymes are protein.
 The conclusion that pure protein can be enzymes was definitively demonstrated
by John Howard Northrop and Wandell Meredith Stanley.

11. Enzymes and X-
ray
Crystallography
 The discovery that enzyme
could be crystallised
eventually allowed their
structures to be solved by X-
RAY crystallography.
 This was first done for
Lysozyme, an enzymes found
in tears, saliva and egg
whites that digests the
coating of some bacteria.
 The structures was solved by
a group led by David Chilton
Phillips and published in
1965.

12. Discovery of Ribozyme and
Restriction Enzymes
 In the early 1980s, research groups led by Sidney Altman and Thomas
Cech independently found that RNAs can also act as catalysts for
chemical reactions.
 This class of catalytic RNAs are known as Ribozymes and the finding
earned Altman and Cech the 1989 Nobel Prize in Chemistry.
 By the late 1960s, and early 1970s, Restriction enzymes were
discovered and characterized by molecular biologists were Aeber,
Hamitton Q . Smith and Daniel Nathane.

13.  “I think that enzymes are molecules that are complementary in
structure to the activated complexes of the reactions that they catalyse,
that is, to the molecular configuration that is intermediate between the
reacting substances and the products of reaction for these catalysed
processes. The attraction of the enzyme molecule for the activated
complex would thus lead to a decrease in its energy and hence to a
decrease in the energy of activation of the reaction and to an increase
in the rate of reaction.”
- Linus Pauling Nature 161(1948):707