Amino-Acid Homopolymers Occurring in Nature (eBook)

Preface 6
Contents 8
Occurrence and Production of Poly-Epsilon-L-Lysine in Microorganisms 10
1 Introduction 11
2 Screening and Discovery of Poly-epsi-l-Lysine Polymers 12
2.1 First Discovery as Dragendorff-Positive Substance 13
2.2 Every Producer Strain Has epsi-PL-Degrading Activity 13
2.3 High Throughput Screening in Agar Plates 14
2.4 Frequent Occurrences Found by Two-Stage Culture Method 14
3 Production Behavior in Streptomyces Strains 15
3.1 Features Shown by the Two Strains 16
3.2 Effects of the Culture Medium 17
3.3 Release of Polymers into the Culture Broth 18
3.4 Development of epsi-PL-Hydrolyzing Activity 19
4 Polymer Structure of epsi-PL in Streptomyces Strains 21
5 Two Advantageous Producers 23
5.1 Streptomyces lydicus USE-11 23
5.2 Streptomyces aureofaciens USE-82 23
6 Production Control and Chain Length Shortening 24
6.1 Cell Density-Dependent Production 24
6.2 Chain Length Shortening by Aliphatic Hydroxy-compounds 25
6.3 Chain Length Shortening Assisted by Sulfated beta-Cyclodextrin 26
7 Poly(Amino Acid) Coproduced with epsi-PL 27
7.1 Poly-gamma-l-Diaminobutanoic Acid 27
7.2 Lariat-Shaped Poly-gamma-l-Glutamic Acid 28
8 Concluding Remarks 29
References 30
Biochemistry and Enzymology of Poly-Epsilon-l-Lysine Biosynthesis 32
1 Introduction 33
2 Genetic System in an epsi-PL Producer, S. albulus NBRC14147 34
2.1 Identification of the Cryptic-Plasmid pNO33 Replicon 34
2.2 Construction of the pNO33-Based Shuttle Vectors for E. coli and Streptomyces Strains 35
2.3 PEG-Mediated Transformation of S. albulus CR1 Protoplast with pLAE001 35
2.4 Conjugal Transfer of the oriT-Vector, pLAE003, from E. coli to S. albulus CR1 36
2.5 Construction of a Genetically Engineered Strain of S. albulus CR1 for epsi-PL Overproduction 37
3 epsi-PL Synthetase 39
3.1 Purification of Pls from S. albulus NBRC14147 40
3.2 Enzymatic Characterization of the Purified Pls 40
3.3 Cloning of the Gene Encoding Pls 41
3.4 Catalytic Mechanism of Pls 43
3.5 Substrate Specificity of Pls 44
4 Concluding Remarks and Future Perspectives 47
References 51
Biochemistry and Enzymology of Poly-Epsilon-l-Lysine Degradation 54
1 Introduction 55
2 Assay for epsi-PL-Degrading Activity 55
3 epsi-PL Degradation by Microorganisms 57
3.1 epsi-PL Degradation by epsi-PL-Tolerant Microorganisms 58
3.1.1 epsi-PL-Degrading Enzyme of Sp. multivorum OJ10 58
3.1.2 epsi-PL-Degrading Enzyme of Chryseobacterium sp. OJ7 60
3.2 epsi-PL Degradation by epsi-PL-Producing Microorganisms 61
3.2.1 Time Course of epsi-PL-Degrading Activity During epsi-PL Production by S. albulus 61
3.2.2 Characterization of epsi-PL-Degrading Enzyme from S. albulus 62
3.2.3 Correlative Distribution of epsi-PL-Degrading and epsi-PL-Producing Activities 63
4 Molecular Genetic Analysis of epsi-PL-Degrading Enzyme of S. albulus 64
4.1 Cloning and Analysis of the pld Gene for epsi-PL-Degrading Enzyme of S. albulus 65
4.2 Biological Function of the pld Gene in S. albulus 65
5 Conclusion 66
References 67
Biotechnological Production of Poly-Epsilon-l-Lysine for Food and Medical Applications 69
1 Introduction 70
2 Microbial Production of epsi-PL 71
2.1 epsi-PL Production in S. albulus No. 346 (Wild-Type) 71
2.2 Improvement of epsi-PL Production Using a Mutant Strain of S. albulus 71
2.3 Optimization of epsi-PL Production for Commercial Supply 72
3 Biological Activities of epsi-PL 73
3.1 Antimicrobial Activities and Antiphage Activity of epsi-PL 73
3.2 Antimicrobial Mechanism of epsi-PL 73
3.3 Microbicidal Activities of epsi-PL 76
3.4 Antimicrobial Profiles of epsi-PL 77
3.5 Safety of epsi-PL 77
4 Application of epsi-PL 78
4.1 Food Preservative 78
4.1.1 Improvement of epsi-PL Preservative Activity by Combination with Other Additives 79
4.1.2 Efficacy for Controlling Food-Borne Pathogens 79
4.2 Medical and Other Applications 80
4.2.1 Suppression of Dietary Fat Absorption 80
4.2.2 Endotoxin Remover and Other Practical Uses 80
5 Concluding Remarks and Future Perspectives 81
References 81
Occurrence and Biosynthetic Mechanism of Poly-Gamma-Glutamic Acid 84
1 Introduction 85
2 Occurrence and Producers 86
2.1 Poly-gamma-dl-Glutamic Acid Producers 87
2.2 Poly-gamma-d-Glutamic Acid Producers 87
2.3 Poly-gamma-l-Glutamic Acid Producers 88
3 Modes of Nonribosomal Amino Acid Polymerization 88
3.1 Thiotemplate Mechanism for Poly-gamma-Glutamate Synthesis 89
3.2 Amide Ligation Mechanism for Poly-gamma-Glutamate Synthesis 90
4 Biosynthesis of Poly-gamma-Glutamic Acid Precursors 91
4.1 l-Glutamic Acid Biosynthesis 92
4.2 d-Glutamic Acid Biosynthesis 92
4.2.1 d-Amino Acid Aminotransferase 92
4.2.2 Glutamic Acid Racemase 93
5 Biosynthesis of Poly-gamma-Glutamic Acid 93
5.1 PgsB Component of Poly-gamma-Glutamic Acid Synthetase 94
5.2 PgsC Component of Poly-gamma-Glutamic Acid Synthetase 94
5.3 PgsA Component of Poly-gamma-Glutamic Acid Synthetase 94
5.4 PgsE Component of Poly-gamma-Glutamic Acid Synthetase 95
6 Concluding Remarks and Future Perspectives 95
References 96
Enzymatic Degradation of Poly-Gamma-Glutamic Acid 101
1 Introduction 102
2 Occurrence of gamma-PGA-Degrading Enzymes 103
2.1 Bacterial Degradation of gamma-PGA 104
2.1.1 Bacillus subtilis 105
2.1.2 Bacillus anthracis 108
2.1.3 Other Microorganisms 109
2.2 Bacteriophage-Related gamma-PGA Degradation 110
2.2.1 PghP of B. subtilis (natto) Phage PhiNIT1 110
2.2.2 Effect of gamma-PGA Degradation on Bacteriophages 111
2.2.3 PghP Distribution 112
3 Stereochemistry of gamma-PGA and Substrate Specificity 113
3.1 Stereochemistry of gamma-PGA 114
3.2 Mode of Action in gamma-PGA Hydrolysis 115
3.3 Modified gamma-PGA 115
4 Structural Analyses of gamma-PGA-Degrading Enzymes 116
4.1 CapD of B. anthracis and GGT of B. subtilis 116
4.2 PghP of Bacteriophage PhiNIT1 118
5 Conclusion and Future Perspectives 118
References 119
Pharmaceutical and Medical Applications of Poly-Gamma-Glutamic Acid 124
1 Introduction 125
2 Poly(gamma-Glutamic Acid)-Drug Conjugates 125
2.1 gamma-PGA-Anticancer Drug Conjugates 126
2.2 gamma-PGA-Antidiabetic Drug (Phloridzin) Conjugates 128
2.3 gamma-PGA-F(ab') Antibody Conjugates 129
3 Self-Assembled Nanoparticles for Drug Delivery System 130
3.1 gamma-PGA-Graft-Phenylalanine Copolymer 131
3.2 gamma-PGA-Poly(lactide) Block Copolymer 137
3.3 gamma-PGA-Chitosan Complex 140
4 Hydrogels for Tissue Engineering 143
4.1 gamma-PGA-Sulfonate as a Heparionid Polymer 144
4.2 gamma-PGA-Sulfonate Hydrogels with FGF-2 Activity 144
4.3 Hydrogel Template Approach for Tissue Engineering 146
5 Concluding Remarks and Future Perspectives 148
References 151
Food Applications of Poly-Gamma-Glutamic Acid 159
1 Introduction 160
2 Physiological Function 160
2.1 Enhancing Intestinal Calcium Absorption 160
2.2 Dental/Oral Care 163
2.3 Antidiabetic Activity 163
2.4 Prevention of Increase of Blood Pressure 164
2.5 Skin Care 165
2.6 Other Functions 165
3 Physical Properties Modifying Function 166
3.1 Antifreeze Activity 166
3.2 Edible Hydrogel/Capsule 167
3.3 Other Functions 168
4 Taste Perception Modifying Function 168
4.1 Masking Taste 168
4.2 Enhancing Taste/Flavor 169
5 Conclusion and Outlook 170
References 170
Index 173