Food Biochemistry and Food Processing (2 edition)

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Enzyme Classification and Nomenclature


H. Ako and W. K. Nip


Introduction
Classification and Nomenclature of Enzymes
General Principles
Common and Systematic Names
Scheme of Classification and Numbering of Enzymes
Class 1: Oxidoreductases
Class 2: Transferases
Class 3: Hydrolases
Class 4: Lyases
Class 5: Isomerase
Class 6: Ligases
General Rules and Guidelines for Classification and
Nomenclature of Enzymes
Examples of Common Food Enzymes
Acknowledgments
References

INTRODUCTION


Before 1961, researchers reported on enzymes or enzymatic ac-
tivities with names of their own preference. This situation caused
confusion to others as various names could be given to the same
enzyme. In 1956, the International Union of Biochemistry (IUB,
later changed to International Union of Biochemistry and Molec-
ular Biology, IUBMB) created the International Commission on
Enzymes in consultation with the International Union of Pure
and Applied Chemistry (IUPAC) to look into this situation. This
Commission (now called the Nomenclature Committee of the
IUBMB, NC-IUBMB) subsequently recommended classifying
enzymes into six divisions (classes) with subclasses and sub-
subclasses. General rules and guidelines were also established
for classifying and naming enzymes. Each enzyme accepted
to the Enzyme List was given a recommended name (trivial
or working name; now called the common name), a system-
atic name, and an Enzyme Commission, or Enzyme Code (EC)
number. The enzymatic reaction is also provided. A common

name (formerly called recommended name) is assigned to each
enzyme. This is normally the name most widely used for that
enzyme, unless that name is ambiguous or misleading. A newly
discovered enzyme can be given a common name and a system-
atic name, but not the EC number, by the researcher. EC numbers
are assigned only by the authority of the NC-IUBMB.
The first book on enzyme classification and nomenclature
was published in 1961. Some critical updates were announced
as newsletters in 1984 (IUPAC-IUB and NC-IUB Newsletters
1984). The last (sixth) revision was published in 1992. An-
other update in electronic form was published in 2000 (Boyce
and Tipton 2000). With the development of the Internet, most
updated information on enzyme classification and nomencla-
ture is now available through the website of the IUBMB
(http://www.chem.qmul.ac.uk/iubmb/enzyme.html). This chap-
ter should be considered as an abbreviated version of enzyme
classification and nomenclature, with examples of common
enzymes related to food processing. Readers should visit the
IUBMB enzyme nomenclature website for the most up-to-date
details on enzyme classification and nomenclature.

CLASSIFICATION AND NOMENCLATURE
OF ENZYMES

General Principles
 First principle: Names purporting to be names of enzymes,
especially those ending in -aseshould be used only for sin-
gle enzymes, that is, single catalytic entities. They should
not be applied to systems containing more than one en-
zyme.
 Second principle: Enzymes are classified and named ac-
cording to the reaction they catalyze.
 Third principle: Enzymes are divided into groups on the
basis of the type of reactions catalyzed, and this, together

Food Biochemistry and Food Processing, Second Edition. Edited by Benjamin K. Simpson, Leo M.L. Nollet, Fidel Toldr ́a, Soottawat Benjakul, Gopinadhan Paliyath and Y.H. Hui.
©C2012 John Wiley & Sons, Inc. Published 2012 by John Wiley & Sons, Inc.

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