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ENZYMES
HISTORY
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Enzymes
from microorganisms are used in ancient cooking |
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Enzymes
from microorganisms are used in ancient cooking Baking, brewing,
alcohol production and cheese-making are examples of enzyme processes
known since prehistoric times.
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The
first enzymatic hydrolysis of starch |
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The
French scientists Payen and Persoz isolated an enzymatic complex
from malt, naming it "diastase", and the Swedish chemist
Jöns Jakob Berzelius described the first enzymatic hydrolysis of starch.
1833
The
modern history of enzymes dates back to 1833 when, in the journal
Annales de Chemie et de Physique, the French chemists Anselme Payen
and Jean-Franois Persoz described the isolation of an amylase complex
from germinating barley and named it diastase. Like malt itself, this
product converted gelatinized starch into sugars, primarily maltose.
In 1835 the Swede J"ns Jacob Berzelius demonstrated that starch
can be broken down more efficiently using malt extract than sulphuric
acid and coined the term catalysis.
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Theodor
Schwann discovers the digestive enzyme Pepzin |
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1836
In
1836, while investigating digestive processes, the German
physiologist Theodor Schwann isolated a substance responsible for
albuminous digestion in the stomach and named it pepsin, the first
enzyme prepared from animal tissue.
Theodor
Schwann was the founder of the theory of modern histology, defining
the cell as the basic unit of animal structure. At the time he was an
assistant at the Anatomisch-Zootonischen Institut in Berlin. Three
years later he became professor of anatomy at the Catholic University
of Louvain, in 1848 professor of physiology and comparative anatomy
at Liege, and in 1880 he retired from teaching.
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Sixty
years of yeast debate |
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What
is the role of yeast in the fermentation process? This question was
heavily debated for almost 60 years.
1839
-1897
What
is the role of yeast in the fermentation process? This question was
heavily debated for almost 60 years.
The
German chemist Jutus von Lieberg and the French chemist Louis
Pasteur never agreed on the answer. After the death of these two
adversaries, two German chemists finally put an end to the debate.
Hans
and Eduard Buchner lay the cornerstone of modern biochemistry when
they demonstrated that cellfree yeast extract could convert glucose
into ethanol and carbon dioxide just like viable yeast cells.
In
1839 the eminent German chemist Jutus von Liebig developed a
mechanistic explanation for the role of yeast in the fermentation
process. He viewed the yeast present in the fermentation mixture as a
decomposing matter that emitted certain vibrations: ... the sugar
atoms suffer a displacement; they rearrange themselves in such a way
as to form alcohol and carbon dioxide.
On
the other hand, alcoholic fermentation was considered to a be
spontaneous reaction until 1858, when the French chemist and
biologist Louis Pasteur proved in a series of publications that
fermentation occurs only in the presence of living cells - a
phenomenon correlated with life - a physiological act, as he called
it. This divergence in the understanding of the nature of yeast in
the fermentation process caused heated debate between Liebig and
Pasteur.
Liebig
died in 1873 and Pasteur in 1895 without the debate being concluded.
Subsequently, however, the German chemists Eduard Buchner and Hans
Buchner discovered in 1897 that a cell-free extract of yeast could
cause alcoholic fermentation. The ancient puzzle was solved; the
yeast cell produces the enzyme, and the enzyme brings about
fermentation.
The
Liebig-Pasteur dispute was thus finally settled, Hans and Eduard
Buchner laying the cornerstone of modern biochemistry by
demonstrating that cellfree yeast extract could convert glucose into
ethanol and carbon dioxide just like viable yeast cells. In other
words, the conversion was not attributable to yeast cells as such,
but to their nonviable enzymes.
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Enzyme
- derived from greek, meaning 'in yeast' |
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1876
In
1876 William Kuhne proposed that the name enzyme be used as the new
term to denote phenomena previously known as unorganized ferments,
i.e. ferments isolated from the viable organisms in which they were
formed. The word itself means 'in yeast' and is derived from the
Greek en meaning in and zyme meaning yeast or leaven. Kuhne may have
had similar views on fermentation to those advocated by the Buchners,
but he failed to provide the experimental evidence required for their validity.
In
1897 the Buchner brothers demonstrated that cell-free extracts from
yeast could break down glucose into ethanol and carbon dioxide.
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Determination
of proteins in food |
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Johan
Kjeldahl developed a method for detecting nitrogen. The method is
used extensively in the determination of protein in foods.
Johan
Kjeldahl, who was head of the Chemical Department at the Carlsberg
Laboratory in Copenhagen from 1876 until his death in 1900, developed
an analytical method for detecting nitrogen in the trinegative state
in certain organic compounds.
The
method was developed in 1883 and is used extensively in the
determination of protein in foods since protein is a macromolecule
made up of nitrogen-containing amino acids linked together. When used
for quantitative protein determination, the percentage of nitrogen
measured is converted to the equivalent protein content using an
appropriate numerical factor. The method was the basis for the
development of quantitative enzymology and general biotechnology.
In
the same year, the botanist, mycologist and microbiologist Emil Chr.
Hansen, who was head of the Department of Physiology at the Carlsberg
Laboratories in Copenhagen from 1879 to 1909, discovered and
developed a method for propagating yeast which made it possible to
produce pure yeast cultures for industrial use. His methods have been
used ever since in scaling up industrial fermentation processes.
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First
commercial production of food with enzymes |
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In
the USA, the Japanese biochemist and industrialist leader Dr Jokichi
Takamine began commercial production of koji from the fungus
Aspergillus oryzae and called it "takadiastase".
1894
During
the early part of the 20th century enzyme technology was also slowly
developing outside Europe. In the Far East, an age-old tradition
prevailed where mould fungi called koji were (and indeed still are)
used in the production of certain foodstuffs and flavouring additives
based on soya protein (shoyu, miso) and fermented beverages (sake,
alcohol). Koji is prepared from steamed rice into which a mixture of
mould fungi is inoculated, the composition of the mixture being
passed down from generation to generation.
This
formed the basis on which Dr Jokichi Takamine developed a
fermentation process for the industrial production of fungal amylase.
In 1891 Takamine filed patent applications in the USA, the UK,
France, Belgium, Canada and Germany for Taka koji from Aspergillus
oryzae cultured on moist rice or wheat bran and for the production
method for koji. It was presumably the first patent for a microbial
enzyme product. The product was called takadiastase. The method of
fermentation suggested by Takamine, the surface culture or semisolid
culture, is still used in the production of certain enzymes.In 1894
Takamine and his family moved to the USA, settling in New York City.
He opened his own private research laboratory, but allowed Parke,
Davis & Company to produce takadiastase commercially. The product
is still used today as a digestive aid.
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Scientists
define the Lock-and-Key theory |
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Emil
Fisher developed the theory of enzyme catalysis and Victor Henry
stated that an enzyme-substrate complex is an essential step in
enzymic catalysis. Michaelis and Menten described enzyme kinetics mathematically.
1894-1913
In
1894 the German chemist Emil Fischer developed the lock-and-key
theory based on the properties of glycolytic enzymes. He determined
that a vital function of enzymes also depends on the stereometric
configuration of the molecules (i.e. the position of the atoms
relative to one another). Fischer was the first to determine the
molecular structures of glucose (or grape sugar) and fructose and to
synthesize them from glycerol in 1890.
Fundamental
enzyme kinetics dates back to 1903. At that time Victor Henri
concluded in Paris that an enzyme combines with its substrate to form
an enzyme-substrate complex as an essential step in enzyme catalysis.
Based on this idea, the general theory of enzyme action was expressed
mathematically by Leonor Michaelis of Germany and Maud Lenora Menten
of Canada in 1913. They postulated that the enzyme E first combines
with its substrate S to form an enzyme-substrate complex ES in a
relatively fast reversible reaction: E + S B ES. The latter complex
then breaks down in a second, slower reversible reaction to yield the
reaction product P and the free enzyme: ES B P + E.
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Enzymes
replace excrements in leather bating |
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For
hundreds of years leather was bated using extracts of excrement. The
Roman writer Pliny reported the use of pigeon droppings for this
process over two thousand years ago. In more recent centuries, dog
excrement was used extensively.
1908-1913
Thanks
to the German scientist Otto Rohm, founder of Rohm and Hass, a
standardized bate called oropon was developed in 1908, putting an end
to the foul practice of using excrement.
Oropon
was based on an extract from the pancreases of slaughtered animals
containing trypsin, one of a mixture of enzymes found in the
digestive system. Since then, all bates have been based on enzyme
preparations. In the latter part of the last century, pancreatic
trypsin was partly replaced by bacterial and fungal enzymes.
For
example, in 1988 Novozymes introduced a new bating enzyme called
Pyraser which is produced by a bacterium.
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The
first compact detergent is launched |
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Most
people think that compact detergents are something new: they are
not! Rohm invented the first compact detergent in 1914!
1914
Burnus
was a revolutionary, new detergent product. The enzyme was so
effective that only a small quantity was required. Burnus was
originally sold in tablet form as a stain remover, one tablet being
mixed with 10 litres of water.
Rohm
and his wife are reported to have tested trypsin at home on their
dirty underwear! They found it was excellent. When soaked overnight,
their clothes became clean and the water became dirty. Rohm had
invented the world's first compact detergent!
Unfortunately,
German housewives were used to bulky washing powders that produced
lots of lather, so they regarded the tablets with suspicion, not
believing that a small tablet could work. Rohm was forced to
reformulate the product as a washing powder and sell it in 50 g boxes.
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Scientists
discover that enzymes are proteins |
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Dr
James B. Sumner of the USA demonstrated that enzymes are proteins
and performed the first crystallization of an enzyme.
1926
Dr
James B. Sumner of the USA demonstrated that enzymes are proteins
and performed the first crystallization of an enzyme.
At
the same time, Danish scientist K. Lindestroem-Lang investigated the
ionization of proteins and laid down a basic formalism for the
purification of enzymes.
The
fact that enzymes are proteins was discovered in 1926 by James
Batcheller Sumner of Cornell University, Ithaca, NY.
Sumner's
research work at Cornell first centred on analytical methods, but
despite his hard work he was unable to obtain any interesting
results. He then decided to isolate an enzyme in pure form, an
ambitious aim never achieved by anyone up to then, but a type of
research suited to his scanty apparatus and meagre laboratory staff.
In particular, he worked with urease.
For
many years his work was unsuccessful, but in spite of the
discouragement of colleagues who doubted whether any enzyme could
ever be isolated in pure form he continued. In 1921, when his
research was still in its early stages, he had been granted an
American-Belgian fellowship and decided to go to Brussels to work
with Jean Effront, who had written several books on enzymes.
The
plan fell through, however, because Effront thought Sumner's idea of
isolating urease was ridiculous. Back in Ithaca, he resumed his work
until finally, in 1926, he succeeded. His isolation and
crystallization of urease met with a mixed response; it was ignored
or disbelieved by most biochemists, but it brought him a full
professorship in 1929 and the Nobel Prize in Chemistry in 1946.
In
the same year, K. Linderstrøm-Lang investigated many
important detailed chemical properties of proteins at the Carlsberg
Laboratory in Copenhagen. The 1924 publication The Ionization of
Proteins laid down a basic formalism for the production of enzymes.
The Lang theory is still the first approximation and remains in use
for many problems where the molecular structure is not known. |
