Tài liệu Lipases and Phospholipases in Drug Development pptx

Edited by
Günter Müller and Stefan Petry
Lipases and Phospholipases
in Drug Development
From Biochemistry
to Molecular Pharmacology
Lipases and Phospholipases in Drug Development
Edited by
Günter Müller and Stefan Petry
Further Titles of Interest
J. Östman, M. Britton, E. Jonsson (Eds.)
Treating and Preventing Obesity
2004. ISBN 3-527-30818-0
T. Dingermann, D. Steinhilber, G. Folkers (Eds.)
Molecular Biology in Medicinal Chemistry
2004. ISBN 3-527-30431-2
A.K. Duttaroy, F. Spener (Eds.)
Cellular Proteins and Their Fatty Acids in Health and Disease
2003. ISBN 3-527-30437-1
H. Buschmann et al. (Eds.)
Analgesics –
From Chemistry and Pharmacology to Clinical Application
2002. ISBN 3-527-30403-7
G. Molema, D.K.F. Meijer (Eds.)
Drug Targeting
2001. ISBN 3-527-29989-0
Edited by
Günter Müller and Stefan Petry
Lipases and Phospholipases

in Drug Development
From Biochemistry
to Molecular Pharmacology
Dr. Günter Müller
Dr. Stefan Petry
Aventis Pharma Germany
Industrial Park Höchst
65926 Frankfurt am Main
Germany


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Readers are advised to keep in mind that state-
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other items may inadvertently be inaccurate.
Preface XIII
List of Contributors XV
1 Purification of Lipase 1
Palligarnai T. Vasudevan
1.1 Introduction 2
1.2 Pre-purification Steps 2
1.3 Chromatographic Steps 3
1.4 Unique Purification Strategies 7
1.5 Theoretical Modeling 9
1.5.1 Model Formulation 9
1.5.1.1 Mobile Phase 9
1.5.1.2 Stationary Phase 10
1.5.1.3 Boundary Conditions 10
1.5.2 Solution 11
1.5.3 Method of Moments 13

1.5.4 Model Evaluation 15
1.5.5 Simulation Results 16
1.5.5.1 Effect of Feed Angle 16
1.5.5.2 Effect of Flow Rate 17
1.5.5.3 Effect of Rotation Rate 17
1.5.5.4 Effect of Column Height 19
1.6 Conclusions 19
1.7 Acknowledgements 20
1.8 References 20
2 Phospholipase A
1
Structures, Physiological and Patho-physiological Roles
in Mammals
23
Keizo Inoue, Hiroyuki Arai, and Junken Aoki
2.1 Introduction 23
2.2 Phosphatidylserine-specific Phospholipase A
1
(PS-PLA
1
) 27
2.2.1 Historical Aspects 27
V
Contents
2.2.2 Biochemical Characterization and Tissue Distribution 27
2.2.3 Structural Characteristics 29
2.2.4 Substrate Specificity 29
2.2.5 Possible Functions 30
2.3 Membrane-associated Phosphatidic Acid-selective Phospholipase A
1

s
(mPA-PLA
1
a and mPA-PLA
1
b) 32
2.3.1 Historical Aspects 32
2.3.2 Characterization and Distribution 33
2.3.3 Structural Characteristics 34
2.3.4 Function 34
2.4 Phosphatidic Acid-preferring Phospholipase A
1
(PA-PLA
1
) 35
2.4.1 Historical Aspects 35
2.4.2 Characterization and Distribution 36
2.4.3 Substrate Specificity 36
2.4.4 Function 37
2.5 KIAA0725P, a Novel PLA
1
with Sequence Homology to a Mammalian
Sec23p-interacting Protein, p125
37
2.5.1 Historical Aspects 37
2.5.2 Characterization and Distribution 37
2.6 References 38
3 Rational Design of a Liposomal Drug Delivery System Based on Biophysical
Studies of Phospholipase A
2

Activity on Model Lipid Membranes 41
Kent Jørgensen, Jesper Davidsen, Thomas L. Andresen,
and Ole G. Mouritsen
3.1 Introduction 41
3.2 Role for Secretory Phospholipase A
2
(sPLA
2
) in Liposomal
Drug Delivery
43
3.3 Lateral Microstructure of Lipid Bilayers and its Influence
on sPLA
2
43
3.4 sPLA
2
Degradation of Drug-delivery Liposomes: A New Drug-delivery
Principle
46
3.4.1 Liposomes Protected by Polymer Coating 46
3.4.2 Biophysical Model Drug-delivery System to Study sPLA
2
Activity 47
3.4.3 Effect of Lipid Composition on sPLA
2
-triggered Drug Release
and Absorption
48
3.4.4 Effect of Temperature on Liposomal Drug Release and Absorption

by sPLA
2
49
3.4.5 Liposomal Drug Release as a Function of sPLA
2
Concentration 50
3.5 Conclusion 51
3.6 Acknowledgments 51
3.7 References 52
Contents
VI
4 Phospholipase D 55
John H. Exton
4.1 Introduction 55
4.2 Structure and Catalytic Mechanism of Mammalian
Phospholipase D
56
4.3 Cellular Locations of PLD1 and PLD2 58
4.4 Post-translational Modification of PLD 59
4.5 Regulation of PLD1 and PLD2 60
4.5.1 Role of PIP
2
60
4.5.2 Role of PKC 61
4.6 Role of Rho Family GTPases 64
4.7 Role of Arf Family GTPases 65
4.8 Role of Tyrosine Kinase 66
4.9 Role of Ral 66
4.10 Cellular Functions of PLD 66
4.11 Role of PLD in Growth and Differentiation 67

4.12 Role of PLD in Vesicle Trafficking in Golgi 68
4.13 Role of PLD in Exocytosis and Endocytosis 68
4.14 Role of PLD in Superoxide Formation 69
4.15 Role in Actin Cytoskeleton Rearrangements 70
4.16 Role in Lysophosphatidic Acid Formation 71
4.17 Role of PA in Other Cellular Systems 71
4.18 References 72
5 Sphingomyelinases and Their Interaction with Membrane Lipids 79
Félix M. Goñi and Alicia Alonso
5.1 Introduction and Scope
5.2 Sphingomyelinases 80
5.2.1 Types of Sphingomyelinases 80
5.2.1.1 Acid Sphingomyelinase (aSMase) 80
5.2.1.2 Secretory Sphingomyelinase (sSMase) 81
5.2.1.3 Neutral, Mg
2+
-dependent Sphingomyelinases (nSMase) 81
5.2.1.4 Mg
2+
-independent Neutral Sphingomyelinases 84
5.2.1.5 Alkaline Sphingomyelinase from the Intestinal Tract 85
5.2.1.6 Bacterial Sphingomyelinase-phospholipase C 85
5.2.2 Sphingomyelinase Mechanism 85
5.2.2.1 Binding of Magnesium Ions 85
5.2.2.2 Binding of Substrate 85
5.2.2.3 Mechanism of Catalysis 86
5.2.3 Sphingomyelinase Assay 88
5.2.4 Sphingomyelinase Inhibitors 89
5.3 Sphingomyelinase–Membrane Interactions 89
5.3.1 Lipid Effects on Sphingomyelinase Activity 90

5.3.2 Effects of Sphingomyelinase Activity on Membrane Properties 91
5.3.2.1 Effects on Membrane Lateral Organization 91
Contents
VII
5.3.2.2 Effects on Membrane Permeability 93
5.3.2.3 Effects on Membrane Aggregation and Fusion 94
5.4 Acknowledgments 96
5.5 References 96
6 Glycosyl-phosphatidylinositol Cleavage Products
in Signal Transduction
101
Yolanda León and Isabel Varela-Nieto
6.1 Introduction 101
6.2 GPI Structure and Hydrolysis by Specific Phospholipases 102
6.3 Diffusible Factors and the Regulation of GPI Levels 104
6.4 IPG Structure and Biological Activities 106
6.5 GPI/IPG Pathway and the Intracellular Signaling Circuit 109
6.6 Acknowledgments 112
6.7 References 113
7 High-throughput Screening of Hormone-sensitive Lipase
and Subsequent Computer-assisted Compound Optimization
121
Stefan Petry, Karl-Heinz Baringhaus, Karl Schoenafinger, Christian Jung,
Horst Kleine, and Günter Müller
7.1 Introduction 121
7.1.1 Lipases in Metabolism 121
7.2 Lipases Show Unique Differences in Comparison
to Other Drug Targets
122
7.3 Lipase Assays 123

7.4 Hormone-sensitive Lipase (HSL) as a Drug Target in Diabetes 125
7.4.1 Biological Role of HSL 125
7.4.2 Characteristics of HSL 126
7.4.3 Inhibitors of HSL 128
7.5 Perspective 134
7.6 References 134
8 Endothelial Lipase: A Novel Drug Target for HDL and Atherosclerosis? 139
Karen Badellino, Weijun Jin, and Daniel J. Rader
8.1 Introduction 139
8.2 Structure of Endothelial Lipase 140
8.3 Tissue Expression of Endothelial Lipase and Its Implications 141
8.4 Enzymatic Activity and Effects on Cellular Lipid Metabolism
of Endothelial Lipase
142
8.5 Regulation of Endothelial Lipase Expression 145
8.6 Physiology of Endothelial Lipase 146
8.7 Variation in the Human Endothelial Lipase Gene 149
8.8 Endothelial Lipase as a Potential Pharmacologic Target 151
8.9 References 151
Contents
VIII
9 Digestive Lipases Inhibition: an In vitro Study 155
Ali Tiss, Nabil Miled, Robert Verger, Youssef Gargouri,
and Abdelkarim Abousalham
9.1 Introduction 155
9.1.1 3-D Structure of Human Pancreatic Lipase 156
9.1.2 3-D Structure of Human Gastric Lipase 158
9.2 Methods for Lipase Inhibition 159
9.2.1 Method A: Lipase/Inhibitor Pre-incubation 162
9.2.2 Method B: Inhibition During Lipolysis 162

9.2.3 “Pre-poisoned” Interfaces 163
9.2.3.1 Method C 163
9.2.3.2 Method D 163
9.3 Inhibition of Lipases by E
600
and Various Phosphonates 164
9.3.1 Inhibition of PPL, HGL and RGL by Radiolabeled E
600
165
9.3.2 Interfacial Binding to Tributyrin Emulsion of Native
and Chemically Modified Digestive Lipases
167
9.3.3 Inhibition of Lipases by Phosphonates and the 3-D Structures
of Lipase-inhibitor Complexes
167
9.3.3.1 Synthesis of New Chiral Organophosphorus Compounds Analogous
to TAG
167
9.3.3.2 The 2.46 Å Resolution Structure of the Pancreatic/Procolipase
Complex Inhibited by a C
11
Alkylphosphonate 170
9.3.3.3 Crystal Structure of the Open Form of DGL in Complex
with a Phosphonate Inhibitor
173
9.4 Inhibition of Digestive Lipases by Orlistat 174
9.4.1 Introduction 174
9.4.2 Inhibition of Digestive Lipases by Pre-incubation
with Orlistat (Method A)
175

9.4.2.1 Inhibition of Gastric Lipases 175
9.4.2.2 Inhibition of Pancreatic Lipases 176
9.4.2.3 Kinetic Model Illustrating the Covalent Inhibition of HPL
in the Aqueous Phase
180
9.4.3 Inhibition of Digestive Lipases During Lipolysis (Method B) 181
9.4.4 Inhibition of Digestive Lipases on Oil Emulsions “Poisoned”
with Orlistat (Method C)
181
9.4.5 Inhibition of Digestive Lipases on Oil Substrate “Poisoned”
with Orlistat (Method D)
184
9.4.5.1 Inhibition of Pancreatic Lipase on Emulsion “Pre-poisoned”
with Orlistat
184
9.4.5.2 Inhibition of Gastric and Pancreatic Lipases on Mixed Films
Containing Orlistat
185
9.4.5.3 Inhibition of Pancreatic Lipase on Oil Drop “Pre-poisoned”
with Orlistat
185
9.5 References 187
Contents
IX
10 Physiology of Gastrointestinal Lipolysis and Therapeutical Use
of Lipases and Digestive Lipase Inhibitors
195
Hans Lengsfeld, Gabrielle Beaumier-Gallon, Henri Chahinian,
Alain De Caro, Robert Verger, René Laugier, and Frédéric Carrière
10.1 Introduction 195

10.2 Tissular and Cellular Origins of HGL and HPL 196
10.3 Hydrolysis of Acylglycerols by HGL and HPL 199
10.3.1 Substrate Specificity 199
10.3.2 Specific Activities of HGL and HPL 200
10.3.3 Lipase Activity as a Function of pH 202
10.3.4 Effects of Bile Salts on the Activity of HGL and HPL 202
10.4 Gastrointestinal Lipolysis of Test Meals in Healthy Human
Volunteers
204
10.4.1 Test Meals 205
10.4.2 Experimental Device for Collecting Samples in vivo 207
10.4.3 Gastric and Duodenal pH Variations 207
10.4.4 Lipase Concentrations and Outputs 207
10.4.5 Lipolysis Levels 211
10.5 HGL and HPL Stability 213
10.6 Potential Use of Gastric Lipase in the Treatment of Pancreatic
Insufficiency
215
10.7 Inhibition of Gastrointestinal Lipolysis by Orlistat for Obesity
Treatment
216
10.7.1 The Lipase Inhibitor Orlistat 216
10.7.2 Design of Clinical Studies for Quantification of Lipase and Lipolysis
Inhibition
217
10.7.3 HGL Inhibition by Orlistat 218
10.7.4 HPL Inhibition by Orlistat 219
10.7.5 Effects of Orlistat on Gastric Lipolysis 220
10.7.6 Effects of Orlistat on Duodenal Lipolysis 221
10.7.7 Effects of Orlistat on Overall Lipolysis 221

10.7.8 Effects of Orlistat on Fat Excretion 221
10.7.9 Weight Management by Orlistat in Obese Patients 222
10.7.10 Conclusions 224
10.8 References 224
11 Physiological and Pharmacological Regulation of Triacylglycerol Storage
and Mobilization
231
Günter Müller
11.1 Metabolic Role of Triacylglycerol 231
11.1.1 Triacylglycerol and Energy Storage 231
11.1.2 Lipolysis and Re-esterification 234
11.1.3 TAG Storage/Mobilization and Disease 236
11.1.3.1 Diabetes Mellitus and Metabolic Syndrome 236
11.1.3.2 Lipotoxicity 238
Contents
X
11.1.3.2.1 b-Cells 238
11.1.3.2.2 Cardiac Myocytes 239
11.1.3.2.3 Molecular Mechanisms 240
11.1.3.3 Inborn Errors of TAG Storage and Metabolism 241
11.2 Components for TAG Storage and Mobilization 242
11.2.1 TAG in Lipoproteins 242
11.2.2 TAG in Adipose Cells 243
11.2.2.1 Enzymes of TAG Synthesis 244
11.2.2.2 Lipid Droplets 246
11.2.2.2.1 Morphology and Lipid Composition 246
11.2.2.2.2 Protein Composition 248
11.2.2.2.3 Biogenesis 252
11.3 Mechanism and Regulation of TAG Mobilization 259
11.3.1 cAMP 259

11.3.2 Phosphorylation of HSL 260
11.3.3 Dephosphorylation of HSL 263
11.3.4 Intrinsic HSL Activity 263
11.3.5 Translocation of HSL 264
11.3.5.1 Mechanism 264
11.3.5.2 Involvement of Perilipins 266
11.3.5.3 Involvement of Lipotransin 268
11.3.6 Intrinsic Activity of HSL 270
11.3.6.1 Feedback Inhibition 270
11.3.6.2 Adipocyte Lipid-binding Protein 272
11.3.7 Expression of HSL 274
11.3.8 Release of Lipolytic Products 275
11.3.8.1 FA Transport 275
11.3.8.2 Glycerol Transport 276
11.3.8.3 Cholesterol Transport 277
11.4 Physiological, Pharmacological and Genetic Modulation
of TAG Mobilization
278
11.4.1 Muscle Contraction 278
11.4.2 Nutritional State 279
11.4.3 Hormones and Cytokines 279
11.4.3.1 Insulin 279
11.4.3.1.1 Molecular Mechanisms 279
11.4.3.1.2 Desensitization 281
11.4.3.2 Leptin 282
11.4.3.3 Growth Hormone 283
11.4.3.4 Glucose-dependent Insulinotropic Polypeptide 283
11.4.3.5 TNF-a 283
11.4.4 ASP 285
11.4.5 Acipimox and Nicotinic Acid 286

11.4.5.1 Mode of Action 287
11.4.5.2 Molecular Mechanism 288
Contents
XI
11.4.5.3 Desensitization 289
11.4.6 Glimepiride and Phosphoinositolglycans 290
11.4.7 Differences in Regulation of TAG Storage and Mobilization between
Visceral and Subcutaneous Adipocytes
292
11.4.8 Up-/Down-regulation of Components of TAG Storage
and Mobilization
294
11.4.8.1 HSL 294
11.4.8.2 ALBP 296
11.4.8.3 Perilipin 297
11.4.8.4 PKA 299
11.4.8.5 ASP 300
11.4.8.6 Caveolin 301
11.5 Concluding Remarks 302
11.6 References 303
Subject Index 333
Contents
XII
Within the last decade the interest in lipases has increased dramatically, and no
doubt, this interest will be maintained in the future. Novel and powerful tools of
molecular biology, crystallography, NMR technology and molecular modeling will
continue to reveal new amino acid sequences and three-dimensional structures of li-
pases. In addition, transgenic and knockout animal models as well as the use of spe-
cific inhibitors will add knowledge about their mode of interaction with lipid sub-
strates, cleavage mechanism and physiological roles in humans.

After having clarified many basic aspects of lipolysis (i.e. structure, function and
regulation of lipases and their catalytic mechanism) the focus will shift to the patho-
physiological role of lipases in metabolic diseases and will result in strategies for
pharmacological intervention.
The common interest of academic and industrial pharmaceutical research is based
on the search for selective small molecule modulators of lipase activity for the devel-
opment of drugs suited to the therapy of diabetes, atherosclerosis, obesity and for in
depth analysis of the underlying molecular defects in nutritional signaling by lipo-
lytic cleavage products.
The discovery of appropriate starting points for the development of potent and
specific inhibitors is still a challenge. In addition to the usual problems of low abun-
dance and purity that enzymologists and structural biologists are generally faced
with, lipases present a unique additional difficulty. Unlike other hydrolytic enzymes,
e.g. esterases or proteases, the substrates hydrolyzed by lipases are insoluble in
water and therefore must be efficiently presented to the enzyme in a separate lipidic
phase. The presence of a suitable second phase apparently leads to increased lipase
activity and may effect subtle but critical changes to the enzyme’s three-dimensional
structure.
This biphasic substrate recognition represents something like the unifying theme
present in all the contributions.
With the help of an international authorship, we have attempted to cover major
aspects of lipase research, from genomics to drug discovery via validation of targets,
structural biology, rational drug design, and drug–lipase interaction.
We are convinced that this book will be a valuable compendium for researchers al-
ready engaged in this fascinating field and will motivate talented young scientists to
enter it.
Frankfurt, November 2003 Günter Müller
Stefan Petry
XIII
Preface

XV
List of Contri butors
Abdelkarim Abousalham
Laboratoire de Lipolyse Enzymatique
UPR 9025/CNRS
31 Chemin Joseph Aiguier
13402 Marseille Cedex 20
France
Alicia Alonso
Dpto. de Bioquímica
Fac. de Ciencias
Universidad del País Vasco
Apdo 644
48080 Bilbao
Spain
Thomas L. Andresen
LiPlasome Pharma A/S
Technical University of Denmark
Building 207
2800 Lyngby
Denmark
Junken Aoki
Faculty of Pharmaceutical Sciences
The University of Tokyo
7-3-1 Hongo, Bunkyo-ku
Tokyo 113
Japan
Hiroyuki Arai
Faculty of Pharmaceutical Sciences

The University of Tokyo
7-3-1 Hongo, Bunkyo-ku
Tokyo 113
Japan
Karen Badellino
Preventive Cardiovascular Medicine
and Lipid Research
University of Pennsylania School
of Medicine
421 Curie Blvd.
Philadelphia, PA 19104
USA
Karl-Heinz Baringhaus
Aventis Pharma Germany
Industrial Park Höchst, Bldg. G 878
65926 Frankfurt am Main
Germany
Gabrielle Beaumier-Gallon
Laboratoire de Lipolyse Enzymatique
UPR 9025/CNRS
31 Chemin Joseph Aiguier
13402 Marseille Cedex 20
France
Frédéric Carrière
Laboratoire de Lipolyse Enzymatique
UPR 9025/CNRS
31 Chemin Joseph Aiguier
13402 Marseille Cedex 20
France
Henri Chahinian

Laboratoire de Lipolyse Enzymatique
UPR 9025/CNRS
31 Chemin Joseph Aiguier
13402 Marseille Cedex 20
France
List of Contributors
XVI
Jepser Davidsen
LiPlasome Pharma A/S
Technical University of Denmark
Building 207
2800 Lyngby
Denmark
Alain De Caro
Laboratoire de Lipolyse Enzymatique
UPR 9025/CNRS
31 Chemin Joseph Aiguier
13402 Marseille Cedex 20
France
John H. Exton
Dept. of Molecular Physiology
& Biophysics
Vanderbilt University School
of Medicine
831 Light Hall
Nashville, TN 37232-0295
USA
Youssef Gargouri
Unité de Lipolyse Enzymatique
ENIS – Ecole Nationale d’Ingénieurs

de Sfax
BPW
3038 Sfax
Tunisia
Félix Goñi
Dpto. de Bioquímica
Fac. de Ciencias
Universidad del País Vasco
Apdo 644
48080 Bilbao
Spain
Keizo Inoue
Faculty of Pharmaceutical Sciences
Teikyo University
Sagamiko, Tsukui
Kanagawa 199-0195
Japan
Weijun Jin
Preventive Cardiovascular Medicine
and Lipid Research
University of Pennsylvania School
of Medicine
421 Curie Blvd.
Philadelphia, PA 19104
USA
Kent Jørgensen
LiPlasome Pharma A/S
Technical University of Denmark
Building 207
2800 Lyngby

Denmark
Christian Jung
Aventis Pharma Germany
Industrial Park Höchst, Bldg. G 878
65926 Frankfurt am Main
Germany
Horst Kleine
Aventis Pharma Germany
Industrial Park Höchst, Bldg. G 878
65926 Frankfurt am Main
Germany
René Laugier
Laboratoire de Lipolyse Enzymatique
UPR 9025/CNRS
31 Chemin Joseph Aiguier
13402 Marseille Cedex 20
France
Hans Lengsfeld
F. Hoffmann-La Roche Ltd.
Pharmaceuticals Division
CH-4070 Basel
Switzerland
Yolanda León
Departamento de Biología
Universidad Autónoma de Madrid
Carretera de Colmenar Km 15
Cantoblanco
28049 Madrid
Spain
List of Contributors

XVII
Nabil Miled
Laboratoire de Lipolyse Enzymatique
UPR 9025/CNRS
31 Chemin Joseph Aiguier
13402 Marseille Cedex 20
France
Ole G. Mouritsen
Department of Physics
University of Southern Denmark
Campusvej 55
5230 Odense M
Denmark
Günter Müller
Aventis Pharma Germany
DG Metabolic Diseases
Industrial Park Höchst, Bldg. H 825
65926 Frankfurt am Main
Germany
Stefan Petry
Aventis Pharma Germany
Industrial Park Höchst, Bldg. G 878
65926 Frankfurt am Main
Germany
Daniel J. Rader
Preventive Cardiovascular Medicine
and Lipid Research
University of Pennsylvania School
of Medicine
654 BRB II/III, 421 Curie Blvd.

Philadelphia, PA 19104
USA
Karl Schoenafinger
Aventis Pharma Germany
Industrial Park Höchst, Bldg. G 878
65926 Frankfurt am Main
Germany
Ali Tiss
Laboratoire de Lipolyse Enzymatique
UPR 9025/CNRS
31 Chemin Joseph Aiguier
13402 Marseille Cedex 20
France
Isabel Variela-Nieto
Inst. de Investigaciones Biomedicas
Alberto Sols
CSIC-Universidad Autónoma
de Madrid
c/Arturo Duperier, 4
28029 Madrid
Spain
Palligarnai T. Vasudevan
Department of Chemical Engineering
University of New Hampshire
Durham, NH 03824
USA
Robert Verger
Laboratoire de Lipolyse Enzymatique
UPR 9025/CNRS
31 Chemin Joseph Aiguier

13402 Marseille Cedex 20
France
Abbreviations
a hydrodynamic radius of the solute (m)
C
m
mobile phase concentration (mol l
–1
)
C
f
feed concentration (mol l
–1
)
C
s
stationary phase concentration (mol l
–1
)
C
H
m
normalized mobile phase concentration
C
H
s
normalized stationary phase concentration
C
H

m
normalized mobile phase concentration in the Laplace domain
C
H
s
normalized stationary phase concentration in the Laplace domain
C
D
drag coefficient
D
m
dispersion coefficient, m
2
s
–1
D
s
diffusion coefficient in the stationary phase, m
2
s
–1
D
?
bulk diffusivity, m
2
s
–1
k mass transfer coefficient, m s
–1
K

eq
equilibrium partition coefficient
L length of the column, m
m
n
n
th
moment about the origin
N Avogadro number
Nu
s
Nusselt number in the stationary phase
Nu
m
Nusselt number in the mobile phase
Pe Peclet number
R particle size, m
r
0
pore radius, m
Re Reynolds number
S Particle surface area per unit column volume, m
–1
Sh Sherwood number
Sc Schmidt number
Greek letters
b internal porosity
e external porosity
m kinematic viscosity, m
2

s
–1
1
1
Purification of Lipase
Palligarnai T. Vasudevan
h
f
feed angle (deg)
x rotation rate (deg h
–1
)
l viscosity of the solvent, kg m
–1
s
–1
l
H
n
n
th
normalized moment
l
n
n
th
moment about the mean
1.1
Introduction
Lipases (EC 3.1.1.3) find wide use, ranging from the food industry, e.g. in cheese

making, to manufacturing, where they can act as catalysts of high specificity and
selectivity. Research has focused on the purification and the characterization of li-
pases from sources as diverse as the unicellular Pseudomonas putida to cod (Gadus
morhua). Aires-Barros et al. [1] have reviewed the isolation and purification of li-
pases, mainly from microbial and mammalian sources, while different purifica-
tion techniques have been reviewed by Palekar et al. [2].
1.2
Pre-purification Steps
Lipases obtained from different sources are usually subjected to certain pre-purifi-
cation steps before they are purified further. Typically, this is a one-step procedure
involving precipitation by saturation with an ammonium sulfate [(NH
4
)
2
SO
4
] solu-
tion. The lipase is thus separated from the extract solution. It can then be sub-
jected to more specific purification steps. In some cases [3–9], the solution is con-
centrated by ultrafiltration to reduce the volume of the solution, and is then sub-
jected to ammonium sulfate precipitation. The increase in lipase activity depends
on the concentration of the ammonium sulfate solution used. Pabai et al. [10]
demonstrated that the maximum increase in lipase activity occurred between 20–
40% of saturation, with a 19-fold increase in purification level. Ammonium sul-
fate precipitation can be combined with other purification steps such as acid pre-
cipitation.
Other pre-purification steps are summarized in Tab. 1.1 (note that the purifica-
tion factors are typical values, and where the range cannot be established, end-val-
ues are reported). Despite the wide range of lipase sources used, the purification
levels obtained from any one pre-purification protocol (for example, ammonium

sulfate precipitation) remain within a certain range.
1 Purification of Lipase
2
1.3
Chromatographic Steps
Most biological materials constitute themselves into a clear or a nearly clear solu-
tion for direct application to chromatographic columns after centrifugation or fil-
tration. Almost all purification protocols use chromatographic steps after the pre-
purification steps. Normally, a single chromatographic step is not sufficient to ob-
tain the required level of purity. Hence, a combination of chromatographic steps
is required. As a rule of thumb, to get a lipase of high purity, as measured by the
level of purification (purification fold) and loss of activity (specific activity), at least
four chromatographic steps are needed.
One might expect the order in which chromatographic steps are applied in a lipase
purification protocol to be of minor importance. However, the actual situation is far
from ideal. For example, a gel filtration step might be optimized to give extremely high
levels of purity for the selected protein but only at the cost of time and sample volume.
Likewise the selection of affinity chromatography as the first step would result in an
extremely high purification factor. However,the cost of the adsorbentmakes the use of
smaller columns and repeated injections mandatory. Hence, the required process
time and the possibility of product loss with/without structural modifications in-
crease. Consequently, there are several practical rather than theoretical reasons
why one should choose certain chromatographic techniques for the early steps
1.3 Chromatographic Steps
3
Tab. 1.1 Summary of the pre-purification steps used and the purification levels typically at-
tained.
No Technique used X-fold increase Reference Source
1 Ammonium sulfate
precipitation

2
(range: 2–4)
11 Human Pancreatic Lipase in
V79 Chinese hamster lung cells
2 Ultrafiltration 1.1
(range: 1–2)
5 Pseudomonas putida 3SK
3 Ultrafiltration and ammo-
nium sulfate precipitation
12 8 Serratia marcescens Sr41 8000
4 PEG suspension 2.3 12 Manduca sexta
5 Hexanol extraction and
Methanol precipitation
2.3 13 Bacillus thermocatenulatus
(DSM 730)
6 Triton X-100 extraction 35 14 Human Hepatic Lysosomal
Acid Lipase
7 Acrinol treatment 50 15 Bacillus sp.
8 Isoelectric focusing 7 16 Pseudomonas nov. sp. 109
9 Alcohol treatment 1.1
10
17
18
Aspergillus niger
Penicillium camembertii U-150
10 Acid treatment 1.8
6.2
17
10
Aspergillus niger

Pseudomonas fragi CRDA 323
11 Acetone precipitation 2.1
7.1
19
20
Pseudomonas sp. KWI-56
Rape (Brassica napus) seedling
and others for the final steps of a protein purification process. The choice is primarily
governed by (1) the sample volume, (2) the protein concentration and viscosity of the
sample, (3) the degree of purity of the protein product, (4) the presence of nucleic
acids, pyrogens and proteolytic enzymes in the sample, and (5) the ease with which
different types of adsorbents can be washed free from adsorbed contaminants and
denatured protein. The last parameter governs the life of the adsorbent and, together
with its purchasing price, the material cost of the particular purification step [21].
The logical sequence of chromatographic steps would be to start with the more
robust techniques that combine a concentration effect with high chemical and
physical resistance and low material cost. The obvious candidates are ion-ex-
change chromatography and, to some extent, hydrophobic-interaction chromatog-
raphy. As the latter often requires the addition of salt for adequate protein bind-
ing, it is preferably applied after salt precipitation or after salt displacement from
ion-exchange chromatography, thereby excluding the need for a desalting step.
Thereafter, the protein fractions can be applied to a more specific and more ex-
pensive adsorbent. The protocol is often finished with a gel filtration step.
It is advisable to design the sequence of chromatographic steps such that buffer
changes and concentration steps are avoided. The peaks eluted from an ion ex-
changer can, regardless of the ionic strength, be applied to a gel filtration column.
This step also functions as the desalting procedure which means that the buffer
used for the gel filtration should be chosen so as to allow the direct application of
the eluted peaks to the next chromatographic step. The different chromatographic
techniques have widely different capacities, even though several of the methods

can be applied on a larger scale. However, in the initial stages of a purification
scheme, it is most convenient to start with the methods that allow the application
of large volumes and which have the highest capacities. Ion-exchange chromatog-
raphy and hydrophobic-interaction chromatography belong to this category, but
any adsorption chromatographic method can be used to concentrate larger vol-
umes, especially in batch operations [21].
The final step aims to remove possible aggregates or degradation products and to
condition the purified protein for its use or storage. The procedure will thus be dif-
ferent depending on the fate of the lipase. Aggregates and degradation products are
preferably removed by gel filtration and if the protein is to be lyophilized, this step is
also used for transferring the protein to a volatile buffer. This can sometimes be
done by ion-exchange chromatography, but other forms of chromatography can,
rarely, do this. If the protein solution is to be frozen, stored as a solution or used
immediately the requirements for specific buffer salts might be less stringent. Sev-
eral of the adsorption chromatographic techniques might be adapted to give peaks of
reasonably high protein concentration. This is an advantage when gel filtration is
chosen as the final step. Gel filtration will always dilute the sample and is often fol-
lowed by a concentration step. The impact of an ion exchange step after the gel fil-
tration step is well illustrated by analyzing data in the purification of lipase from
Penicillium camembertii [18]. The impact of the latter step is minimized due to the
use of a more specific purification step before it. Conversely, an ion exchange step
before the gel filtration step is remarkably efficient.
1 Purification of Lipase
4