Table Of ContentPage i
Surface Activity of Proteins
Chemical and Physicochemical Modifications
edited by
Shlomo Magdassi
The Hebrew University of Jerusalem
Jerusalem, Israel
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Page ii
Library of Congress Cataloging-in-Publication Data
Surface activity of proteins : chemical and physicochemical
modifications / edited by Shlomo Magdassi.
p. cm.
Includes index.
ISBN 0-8247-9532-6 (hardcover: alk. paper)
1. Protein engineering. 2. Proteins—Surfaces. 3. Proteins—
Chemical modification. I. Magdassi, Shlomo.
TP248.65.P76S87 1996
660'.63—dc20 96-25981
CIP
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Copyright © 1996 by Marcel Dekker, Inc. All Rights Reserved.
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Current printing (last digit):
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PRINTED IN THE UNITED STATES OF AMERICA
Page iii
Preface
Proteins are biopolymers that are encountered in many
applications, such as food emulsions, hair conditioners,
photographic emulsions, and various medical diagnostic
products. Many of these applications are frequently based on
the unique surface activity of the proteins, which is reflected in
functional properties such as foaming, emulsification, and
gelling. The proteins are composed of polymeric chains
containing many hydrophobic and hydrophilic domains, often
giving the molecules an amphipathic structure somewhat
similar to that of polymeric surfactants.
Because the functional properties of the proteins are strongly
dependent on their molecular characteristics this should be
taken into account in order to select the proper protein for an
application.
In general, using a protein in a given application requires a
combination of several properties, such as gelling with
emulsification, adsorption with steric stabilization, and so forth.
Improved functional properties can often result from
enhancement of the surface activity of the protein. Alteration of
surface activity of proteins can be achieved by various methods,
and among them chemical modifications seem to be the most
promising. This book deals with the modification of the surface
activity of proteins from two points of view: first a description
of specific modification methods, such as increasing the
negative charges by succinylation, or attachment of surfactant
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molecules without formation of covalent bonds, and second
evaluation of the implication of the various modifications on
the surface activity, using examples of specific systems and
applications.
The book gathers several approaches to modifying the surface
activity of proteins, and therefore it contains both theoretical
and practical descriptions. After an introductory chapter
describing the basic phenomena related to the behavior of
proteins at various interfaces, the following modification
methods are reviewed: attachment of hydrophobic groups,
increasing the anionic charges, deamidation and
phosphorylation, formation of protein–polysaccharide
conjugates, and proteolysis and linking of various functional
groups by enzymatic reactions. These chapters are followed by
a discussion of noncovalent modifications, such as binding of
surfactants to proteins and denaturation of globular proteins.
Some of these modifications are presented in the last chapter,
which focuses on applications of proteins in food products.
Other methods, such as attachment of positively charged groups
to the protein, are not included in the book, mainly because of
the lack of information linking modification to specific surface
activity. Some of the modifications discussed here have already
been applied in various products. Sometimes they are used
unknowingly, for example, in cosmetic products containing
both surfactants and proteins.
I hope that the scientific information and the description of the
possible approaches to altering functional properties and
surface activity of proteins presented in this book will be useful
to scientists interested in understanding the behavior of proteins
at interfaces, as well as to those who wish to find new
applications and products based on proteins.
Page v
Contents
Preface iii
Contributors vii
1. Introduction: Surface Activity and Functional Properties of Proteins 1
Shlomo Magdassi and Alexander Kamyshny
2. Enhanced Hydrophobicity: Formation and Properties of Surface-Active Proteins 39
Shlomo Magdassi and Ofer Toledano
3. Increased Anionic Charge: Conformational and Functional Properties 61
K. D. Schwenke
4. Deamidation and Phosphorylation for Food Protein Modification 91
Frederick F. Shih
5. Preparation and Functional Properties of Protein–Polysaccharide Conjugates 115
Akio Kato
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6. Enzymatic Modification as a Tool for Alteration of Safety and Quality of Food 131
Proteins
Gyöngyi Hajós
7. Denaturation of Globular Proteins in Relation to Their Functional Properties 181
Jacques Lefebvre and Perla Relkin
8. Protein–Surfactant Interactions 237
Malcolm N. Jones
9. Factors Affecting Applications of Native and Modified Proteins in Food 285
Products
M. E. Mangino and W. James Harper
Index 323
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