Food Biochemistry and Food Processing

6

Enzyme Classification and

Nomenclature

H. Ako and W. K. Nip*

135

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

Acknowledgement

References

INTRODUCTION

Before 1961, researchers reported on enzymes or

enzymatic activities with names of their own prefer-

ence. 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 Bio-

chemistry and Molecular Biology, IUBMB) created

the International Commission on Enzymes in con-

sultation with the International Union of Pure and

Applied Chemistry (IUPAC) to look into this situa-

tion. This Commission (now called the Nomen-

clature Committee of the IUBMB, NC-IUBMB) sub-

sequently 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 systematic name, and an

Enzyme Commission, or Enzyme Code (EC) num-

ber. The enzymatic reaction is also provided. A com-

mon 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. Another

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 nomenclature is now available

through the website of the International Union of

Biochemistry and Molecular Biology (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

*Corresponding contributor. examples of common enzymes related to food

Food Biochemistry and Food Processing

Edited by Y. H. Hui

Copyright © 2006 by Blackwell Publishing