Food Biochemistry and Food Processing (2 edition)

BLBS102-c06 BLBS102-Simpson March 21, 2012 12:6 Trim: 276mm X 219mm Printer Name: Yet to Come

6

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.

109