Chemistry Reference
In-Depth Information
‡
X
‡
∆∆
G
cat
(the reduction
in
∆
G
by the
catalyst)
Uncatalyzed
‡
G
Catalyzed
A + B
P + Q
A + B
P + Q
Reaction coordinate
Fig. 1.1
Lowering the activation energy of a reaction.
sugar. He found that the sugar was fermented even when there were no living yeast cells
present.
In 1926, Sumner was able to obtain the first enzyme in pure form. He isolated and
crystallized the enzyme urease from jack beans.
In the middle of the nineteenth century, Northrop and Stanley developed a complex
procedure for isolating pepsin. Their precipitation technique has since been used to crystallize
many enzymes. A few years later, for the first time, an enzyme (a protease) was produced
by fermentation of
Bacillus licheniformis
. In this way, large-scale production of enzymes
became possible, thus facilitating the industrial application of enzymes.
In 1969, the first chemical synthesis of an enzyme was reported. Since then thousands
of enzymes have been studied by X-ray crystallography and nuclear magnetic resonance
(NMR). Application of genetic engineering techniques improved enzyme production effi-
ciency and even allowed improvement of the properties of specific enzymes by means of
protein engineering and evolutionary design. In 2004, the first computer-designed enzymes
were reported.
1.2
NOMENCLATURE OF ENZYMES
Enzymes are usually named according to the reaction they carry out. Typically, the suffix
'
ase
' is added to the name of the substrate (e.g. glucose-oxidase, an enzyme which oxidizes
glucose) or the type of reaction (e.g. a polymerase or isomerase for a polymerization or
isomerization reaction). The exceptions to this rule are some of the enzymes studied orig-
inally, such as pepsin, rennin and trypsin. The International Union of Biochemistry (IUB)
initiated standards of enzyme nomenclature which recommend that enzyme names indicate
both the substrate acted upon and the type of reaction catalyzed. Detailed information on
nomenclature can be found on the IUB homepage.
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